Developing a Successful Defensive AI

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by Mat McBriar


[edit] Overview

  • If you're new to being a Defensive Coordinator you may need to implement the Defensive AI or change the existing mess that might of been created for you.
  • The Defensive AI may look complicated, but by keeping things simple and double checking your inputs, you shouldn't have any major problems.
  • Creating your own "playbook" is not only fun, but it is quite rewarding when your team follows your gameplan and holds your opponent to only a few points (or none at all!).

[edit] I Don't Understand the Defensive AI Interface

[edit] What about the Basic Defensive Tactics?

  • By creating a defensive AI gameplan the basic defensive tactics will become almost obsolete. They still hold value as any input for a "Basic Setting" will revert back to your basic tactics.
  • It's generally a good idea to keep these basic settings fairly conservative. You don't need to set the blitz percentage (0% will do fine), but the splits for pass defense/run defense, run inside/run outside, underneath man-man/zone, and defend short/medium/long should all be filled with conservative outputs.
Basic Defense Tactics

[edit] Overview of how the Defensive AI works

From the team Defensive AI page (located near top of page):

  • The playcalling engine will work its way down from the top to the bottom of your AI inputs until it finds a match.
  • When the engine finds a match, it will make the defensive play call based on the outputs listed underneath that input.
  • If you want to have multiple possible play calls for one situation, add multiple outputs and adjust the "Pct Chance" field to adjust how likely it will be to call that play.
  • If you leave a field blank, there are no matching inputs for a situation, or there are no outputs listed, play calling will default to your "basic" settings and general football logic.
  • Special teams plays (punt return, kickoff return) will always be called in the correct situations, automatically.
How the defensive AI works

[edit] Selecting a Base Defense

Select base defense
  1. When selecting a base defense, you have two options.
    • The first (and the default) is a 4-3 (4 Defensive Linemen, 3 Linebackers)
    • The second option is a 3-4 (3 Defensive Linemen, 4 Linebackers)
  2. AI does not have to be enabled to select the 3-4 defense. You can use the 3-4 without using the advanced AI.
  3. Which should I choose, is one better than the other?
    • People may argue that one base defense outperforms the other, but it is mostly dependent on your team's personnel. You most likely will not be using one base defense exclusively in your formations anyways, but there are multiple cases in which a 3 man or 4 man front would be completely acceptable.
    • If you are favoring a lot of 3 man fronts (3-4 defense), you are going to want to make sure the starter in the DT spot gets ample playing time because the DT is not used in the 3-4 defense. In the 3-4 defense your defensive line is made up of a LE, NT, and RE (based on the GLB depth chart).
      • If you have 3 defensive tackles I would recommend making sure you place your starting DT on the NT depth chart position. Perhaps place him as the #3 and run a 98/99 energy sub-out ratio.
      • Just remember because you are playing a 3-4 you will essentially need less depth at NT/DT and more depth at LB.

[edit] Which Inputs and Outputs do I need

  1. Before we jump into which inputs/outputs the first thing we need to do is check that little box that says "Enable Defense AI? (required for these settings to work)". It is located near the top of the page right above where you selected your base defense.
  2. The second thing you need to do is delete all the existing inputs/outputs. If someone already has created a Defensive AI, make sure to save their existing work. You can do this by entering a "Preset Name" and clicking "Save Current as Preset". This is found at the very bottom of the page.
Saving or loading a preset

So I can just use those formations as my inputs?

  1. could, but your Defensive AI might be a little weak in certain situations. What we have to understand is that on a 3rd and Long if your opponent comes out in a Pro Set, we probably aren't going to see a FB Belly or a Short Curl. You're most likely going to see the Post Corner play, which is a long pass.
  2. Ok, I get it...I need to make Formation Inputs based on yardage and downs. How do I have my inputs only activate at certain yardages/downs?
    Add New Input
  3. Once you create an input you are going to see a bunch of drop down menus and boxes that you can fill out. (to create a new input just click "Add new input", which is located underneath where you selected your base defense)
    • You don't have to fill out all the boxes (Score Difference and Time Remaining in quarter for example don't need to be filled out)
    • Focus on the "Opponent's Formation", "Number of WR's in Set", "Down", and "Yards to first down" areas.
      • Important- If you want to signify a 3 WR set, the Number of WR's in Set boxes would be filled with "Between 3 and 3"
      • Important- The Yards to first down boxes say "between ___ and ___". These numbers do not really mean between they are inclusive. If you say between 5 and 10, 5 and 10 will be included in the span. In short, it's greater than or equal to/less than or equal to rather than greater than/less than.
Input Options to Focus on

[edit] List of Inputs to Use for a Fairly Deep AI with Some Overlap

(Special Thanks to Mike Rogers for the listed inputs, with some slight tweaking by myself to his original list)

  • Goal Line
  • Inside the 3
  • Inside the 10
  • 5 WR Very Long Yardage (7-99 yards, 3rd/4th down)
  • 3 WR Very Long Yardage (7-99 yards, 3rd/4th down)
  • 2 WR Very Long Yardage (7-99 yards, 3rd/4th down)
  • Weak I Short Yardage (0-2 yards, 3rd/4th down)
  • Strong I Short Yardage (0-2 yards, 3rd/4th down)
  • Singleback Short Yardage (0-2 yards, 3rd/4th down)
  • Pro Set Short Yardage (0-2 yards, 3rd/4th down)
  • I-Form Short Yardage (0-2 yards, 3rd/4th down)
  • Shotgun 3 WR Short (0-2 yards, 3rd/4th down)
  • Strong I Medium Yardage (2-4 yards, 3rd/4th down)
  • Weak I Medium Yardage (2-4 yards, 3rd/4th down)
  • Pro Set Medium Yardage (2-4 yards, 3rd/4th down)
  • Singleback Medium Yardage (2-4 yards, 3rd/4th down)
  • Shotgun 3 WR Medium Yardage (2-4 yards, 3rd/4th down)
  • I-Form Medium Yardage (2-4 yards, 3rd/4th down)
  • Strong I Long Yardage (4-7 yards, 3rd/4th down)
  • Weak I Long Yardage (4-7 yards, 3rd/4th down)
  • Pro Set Long Yardage (4-7 yards, 3rd/4th down)
  • Singleback Long Yardage (4-7 yards, 3rd/4th down)
  • Any I-Form Long Yardage (4-7 yards, 3rd/4th down)
  • 5 WR
  • Shotgun 3 WR
  • I-Form 3 WR
  • Singleback 3 WR
  • Weak I
  • Strong I
  • Pro Set
  • 2 TE
  • I-Form Normal

Quarter 4 Specific

  • 100 secs, 2-3 WR (100 seconds to go, 0-3 WR)
  • 2 Minute Drill Big Lead (120 secs to go)
  • Hail Mary Defense (Prevent)

[edit] Developing an Output

So we know how to create an input, but now we've got to move on to the outputs. We create an output by clicking on the "Add New Output" link located underneath our input.

Add New Output
  1. Pct Chance - The percent chance option is going to be at default listed as 100%. This is what we want. GLB does not have a "trickery" factor and the offense does not learn or adapt to what you are doing. Mixing up blitzes/formations will not outsmart the O-line, QB, or the offense. Therefore we only need 1 output per input.
  2. Formation - From the formation drop down menu we are given a few options.
    • 3-4 (3 Defensive Linemen, 4 Linebackers, 2 CBs, 2 Safeties)
      • LE, NT, RE, LOLB, LILB, RILB, ROLB, CB1, CB2, FS, SS (No DT)
    • 4-3 (4 Defensive Linemen, 3 Linebackers, 2 CBs, 2 Safeties)
      • LE, NT, DT, RE, LOLB, MLB, ROLB, CB1, CB2, FS, SS (No LILB, RILB)
    • 4-2-5 Nickel (4 Defensive Linemen, 2 Linebackers, 3 CBs, 2 Safeties)
      • LE, NT, DT, RE, MLB, LOLB, CB1, CB2, CB3, FS, SS (No ROLB)
    • 4-1-6 Dime (4 Defensive Linemen, 1 Linebacker, 4 CBs, 2 Safeties)
      • LE, NT, DT, RE, MLB, CB1, CB2, CB3, CB4, FS, SS (No ROLB, LOLB)
    • 3-1-7 Quarter (3 Defensive Linemen, 1 Linebacker, 5 CBs, 2 Safeties)
      • LE, NT, RE, MLB, CB1, CB2, CB3, CB4, CB5, FS, SS (No DT, ROLB, LOLB)
    • 3-3-5 Nickel (3 Defensive Linemen, 3 Linebackers, 3 CBs, 2 Safeties)
      • LE, NT, RE, LOLB, MLB, ROLB, CB1, CB2, CB3, FS, SS (No DT)
    • 3-2-6 Dime (3 Defensive Linemen, 2 Linebackers, 4 CBs, 2 Safeties)
      • LE, NT, RE, MLB, ROLB, CB1, CB2, CB3, CB4, FS, SS (No DT, LOLB)
  3. Defensive Shells - You are given a few choices ranging from Cover 0 to Cover 4. You are going to want to select a Cover 0, Cover 1, or Cover 2. The Cover 3 and Cover 4 are not very effective for GLB purposes. Some teams may be compelled to play a Prevent style Cover 4 late in games when they are winning, but this isn't necessary. There is no need to play a Cover 4, giving the opposing teams easy first downs. You are much better off making them fight their way to the endzone.
    • Cover 0 - Everyone is placed in man coverage and there is no "last man". Typically, the FS will cover a WR or HB while the SS will double up on the TE.
    • Cover 1 - The FS is placed as a last man. The Cover 1 is fairly safe from giving up huge plays for TDs, mainly because the FS plays a deep centerfield (perhaps too deep). He is effectively useless as he will back pedal to the point where he is out of the range to make any sort of deflection or interception.
    • Cover 2 - Both the FS and SS are placed. This is the typical coverage shell and if you use the "Basic" setting you will see mostly Cover 2 being used. The FS and SS will get involved on medium and long passes and can actually help out, unlike with the Cover 1.
    • Cover 3 - The FS is back in a centerfield type role with the Cover 3. The other two "safeties" are actually the CBs. Your linebackers will end up playing man-man against a WR.
    • Cover 4 - This is a Prevent style defense. The Cover 4 places 2 CBs, the FS, and the SS deep.
  4. Underneath Coverage - The Underneath Coverage setting is going to do one of two things. If you set it towards Man to Man, your LBs will lineup against who they are covering. If this happens to be a HB or FB they will start behind the D-line and immediately move to where the HB/FB runs to. If a LB is playing man to man against a HB who ends up blocking, the LB will simply blitz. The Zone setting will force your LBs to back pedal upon the snap. They will then proceed to pickup and cover any receiver in their respective area.
    • Man to Man is the correct choice 95% of the time. There are a few situations in which zone would actually be a better option. The passing coverage while using zone is better than man to man if you are outmatched.
    • Do not play zone against the run, with the linebackers backing up you basically will be giving the opposing team free yards if they get through the defensive line.
  5. Coverage Distance - This input is going to reflect upon the distance in which the safeties/CBs are standing at the start of the play. (all dependent on which coverage shell you're in)
    • Short
    • Medium
    • Long
  6. Play Focus - Some players in the GLB community will tell you that Play Focus overrides the Individual Tactics. This is completely incorrect. Play Focus merely controls the distance the LB corps plays away from the defensive line.
    • Run Focus (stack the box more)
    • Pass Focus (stack the box less)
    • Balanced
  7. LB Shift - This controls whether your linebackers deviate from the center position. If the linebackers are in man coverage and one if lined up directly on the TE, he will not shift. The other linebackers however will fill his void.
    • Strong Side Shift (more towards the TE)
    • Weak Side Shift (away from the TE)
    • Center Shift (no shift)
  8. Blitzing - Blitzing can be a little complicated due to having to set a "Max # of Blitzers" as well as "Chances". Going back to what I stated earlier, you cannot trick opposing offenses. There are only a few cases in which you would blitz someone less than 100% of the time. They would just be in risky situations. For example, you may feel you can take more chances earlier in the game or if your team is losing you may feel you need to blitz more to create more pressure on the QB and perhaps cause an interception.
    • For our purposes you only need to use 100% chances. A very developed defensive AI may have score/quarter based blitzing differences but it is in no means necessary. Having these can sometimes just make things harder to adjust.
    • A Complicated Warning: If we were in a 3-2-6 formation and we put the max blitzers at 2 while inputting the LOLB and LILB to blitz, we aren't going to see a blitz if our basic settings for blitz chance are at 0. If in our basic settings we had our blitz chance set at 100, 2 blitzers would be randomly chosen unless the defensive coordinator inputs 0's for the positions.
    • Remember that in certain formations there may not be a ROLB, CB5, etc. In a defensive formation that involves 2 linebackers, the MLB and LOLB will be placed onto the field.

[edit] Some Common Blitzes Found in GLB

  • CB3/CB5 from a Quarter Defense
  • MLB/ROLB from a general 4-3, shifted weakside
  • MLB/LOLB from a general 4-3, shifted strongside
  • MLB/SS from a general 4-3
  • CB3, CB4, or both from a Dime Defense, against a 2 or 3 WR set. Teams will sometimes use a defense in which there is one more CB than WR and blitz the extra CB.

[edit] Word Of Caution

  • Remember that the SS/LOLB is generally covering the TE and the FS/ROLB/MLB is generally covering the HB (assuming man coverage). This is key as you'll regret blitzing both the SS and LOLB if you are leaving a TE wide open in the middle of the field. Likewise a large portion of teams get burned by the HB Fly because they are sending the LB blitzing who is otherwise responsible for the HB in coverage.

[edit] Ordering Your Defensive AI Inputs

  • One of the most important things involved with any AI (both offensive and defensive) is the order of your inputs. The order of your inputs represents priority. If two inputs match a certain situation, the one listed at higher up on your defensive AI will overrule the other. Also, just like the offensive AI we have quarter specific overrides. If you put an input under any of the Quarter Specifics it will override your General Settings. To be honest you probably don't need to place any quarter specific inputs.
  • Note: One of the most common mistakes lies with the "I (any variation)". Make sure to place this input near or at the bottom of your defensive AI. If you place it above any Weak I or Strong I formation inputs it will simply use the "I (any variation)" input anytime an I-Form type play arises.

[edit] Tips

  • Double check your inputs/outputs. It's very easy to forget to input something or to input something incorrectly. This can give your opponent an easy score if you don't catch your mistake.
  • Steal from your opponents. Your opponents can be a great source for new inputs/outputs for your defensive AI. By simply watching the play by play of an opponent you can learn a lot. Don't just limit yourself to teams within your league, either. Remember that there are probably differences in personnel between your team and a USA Pro League organization. You may still find an input that you can alter to fit your team's needs.
    • To identify a play, simply take these steps to determine what you're looking at.
      • Count the defensive linemen, linebackers, and secondary to figure out which formation they are in.
      • Identify which Coverage Shell they are using. Most teams are going to use Cover 0, Cover 1, or a Cover 2. The key to figuring out which shell they are using is to watch the FS. Generally in a Cover 0 the FS will cover the HB if he is running a route while the SS will cover the TE. Anytime you see the FS immediately cover someone, you know it's a Cover 0. Cover 1 will have the FS as a deep center fielder, and Cover 2 will have the FS as well as the SS helping out on deeper pass routes.
      • Determine the Play Focus as well as if there are any LB shifts. Gauge the LBs depth (Are they pushed up against the defensive line? If so, we know this is the Run Focus). The shifts are easy to pick out, just remember a strong side shift moves the LBs closer to the TE and likewise a weakside shift moves them away from the TE.
      • Figure out the Coverage Distance. This can be tricky to identify and a lot of teams will use the basic setting. You may have to view multiple plays of the same formation to figure out what the other team is using. Just remember to see how deep the SS is playing. You can basically figure out his depth based on his relation to the FS. If he is standing almost as another LB, this is the short coverage distance. If he is just barely in front of the FS, this is the medium coverage distance. If he is lined up parallel to the FS, this is the long coverage distance.
        4-3 Cover 1 Weak Shift
    • See who is blitzing. Sometimes a team may blitz players besides the LB corps. Make sure to check if they are blitzing a CB or SS. Sometimes this can go unnoticed if you aren't careful. If you see a player who blitzed but aren't sure what position he is in, just check the Offense/Defense list that sits beside the replay window. If you have the player's name (from mousing over the respective dot) you can determine what position they are playing in. This can be especially useful to determine the differences between CB1, CB2, etc.
  • Don't try to bring NFL plays into GLB. Though it may seem like a brilliant idea you have to remember a real life NFL player is going to react better as well as take better routes running to the ball. Mimicking the "Tampa 2" won't work because you can't explain to your dot that he needs to cover a certain area. You are limited by the output settings.
  • Don't get caught blitzing a slow LB. Blitzes can be your best friend or your worst nightmare. By blitzing you are leaving someone in single man coverage or even leaving someone wide open. If you get caught blitzing a slow player you will essentially be giving enough time for the play to develop and for the QB to find the open receiver. Blitzes need to be quick to be efficient. You can get away with blitzing a slow player simply to draw an offensive linemen (mainly the RG) but that is about it.
  • Utilize scrimmages and games against lesser teams to the fullest (gutted teams, lower leveled slow built teams, etc.). Be VERY careful testing new things in your season games or in a tight game. You should not be implementing new plays that you haven't tested for a big game that is coming up.
  • Label your inputs and outputs. Doing so will make things much easier to edit down the road. I tend to label my inputs by the name of the formation/set (i.e. Shotgun 3 WR) and my outputs list the details of the defensive set (i.e. 4-1-6, Cover 1, Man-Man, Pass Focus, Strong Side Shift).
  • Always weigh risk and reward with blitzing. When you blitz a player there is always going to be a downside and an upside. Sure you are increasing pressure on the QB and in some cases almost guarantee yourself a sack or hurry, but if you are leaving a man wide open or leaving a LB in single man coverage against a WR, you may want to rethink things. Always assume the worst will happen, especially when matching up against a successful team. If your blitz is easily picked up by the opposing team, than you have just put yourself at a severe risk for a big play.
  • Pressure creates interceptions. Forcing a QB to throw the ball before he wants to will yield in more pass deflections as well as interceptions. Turnovers are game changers and can help your team beat someone who may out-level you. You probably have heard on the GLB forums that game tactics are the savior for teams who are underleveled and this is completely true. A successful defensive AI can make up for a disadvantage in personnel.
  • You don't need to blitz or stack the line of scrimmage to stop the run. Sometimes allowing your LBs to react and shoot through a hole is a better option than pushing everyone towards the defensive line. You may find that when your LBs start close to the line of scrimmage they may get blocked and the HB will get into the secondary. A balanced or pass focus will sometimes yield a better result than a run focus against a run play. (Don't let the names fool you into thinking what is best!)
  • Gauge how aggressive your particular AI will need to be in an upcoming game. One defensive AI will not work optimally against every team in GLB. It's my personal belief that the higher level team you face, the more pressure you need to get on them. This means being a little more aggressive than if I was playing a team in which my own team was favored. The general idea can be verified by comparing a level 20 QB to a level 36 QB. The level 20 QB is probably not going to have the vision and throwing that the level 36 QB will have. Just on this alone you know the level 36 QB is going to be better at finding an open target as well as delivering a better pass. Therefore you can't allow him all the time in the world to go through his progressions. The level 36 QB will simply shred apart a very conservative defense in which his WRs outmatch the secondary.
  • Do not limit yourself to using only a 3 man front (basically the 3-4) or only a 4 man front (4-3). You can favor one or the other but there are situations that may just call for a 3 or 4 man front.

[edit] Common Mistakes

  • Forgetting to fill in the Opponent's Formation drop down menu, resulting in an "Any Formation" input.
  • Forgetting to set the Max # of Blitzers.
  • Blitzing someone who isn't on the field.
  • Changing your AI while you aren't sober. I can't tell you how bad an idea this is, and yet so many GMs have done it. This generally has negative results.
  • Blitzing a FS out of a Cover 1 or blitzing a SS out of a Cover 2. These are just terrible ideas.
  • Blitzing anyone out of a Cover 4
  • Blitzing the wrong CB, leaving a WR wide open.


[edit] Ask Mat McBriar

Which positions do you like to blitz?

  • Some GMs feel compelled to place one more CB on the field than there are receivers. They then in turn blitz one of the CBs. This can be useful but it's not really my style. I prefer to send multiple blitzers or overload one side. If I'm going against a Shotgun 3 WR set, I like to use a 3-1-7, Cover 0, while blitzing CB3 and CB5. I'll sometimes combo that with a weakside or strongside shift and send either my MLB or LOLB. It isn't really necessary to do so, it just isn't worth having a LB standing around. Anytime you see a replay with a LB just standing around not covering anyone or blitzing (typically happens with the ROLB) try sending them on a blitz. It can't hurt.

Which coverage shell is best to use?

  • There is no definitive "best" shell to use and it's all dependent on the situation. I'm not too big on the Cover 1. It is somewhat safe against giving up long TDs due to the FS playing a deep centerfield, but the FS serves almost no use in the play. It's basically playing a 10 man defense. For that reason, I prefer to play Cover 0 and Cover 2. I do take upon a good amount of risk with playing Cover 0 while blitzing, but I make sure my players are getting pressure when they blitz. I live for the pick-six.

How do I stop the ______ play?

  • Some teams may attempt to run a play over and over (lately we've seen teams do this with the Off Tackle run). Certain plays may appear difficult to stop but there is always an answer. You may weaken your defense against another play from the same formation, but it goes back to risk vs reward. Don't forget that you can shift around players from your depth chart. Maybe you want to move your fastest LB to MLB for a game just to aid in a certain blitz.

Where can I get more help with my Defensive AI?

  • The GLB forums are a very useful tool as is the GLB Wiki. Perhaps you may find some value joining the Defensive Coordinator Private Forum. Teammates and friends alike can be great for sharing knowledge. Don't shy away from posting on the GLB forums for help if you are really stuck. There is a whole section on the GLB forums designated for Tactics Discussion. You aren't the only one who may be confused on a certain topic. If worst comes to worst you can private message a mod or myself. I'm not going to GM for your team or upload a gameplan but I'll gladly answer any questions you may have.
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