In real football, gap control is essential. In Madden, there isn't any true gap control, though there is some basic gap fill logic for the linebackers that you can see in action on replays, but it is just that:- Basic.
There certainly isn't any 2-gapping by the defensive line in Madden. The closest you can get to true gap assignments is to pretend you are teaching a 4-3 defensive style of one gap and call alignments that match. The following is from Monte Kiffen's 1987 Vikings 4-3 Defense.
Take all of this information and just imagine you are using 34 personnel. I'll even help you with your imagination by using MSPaint to make a couple changes to the letter identifications.
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So, at his point we have discussed gap control from a 43 defense, and how to apply it despite Madden's limitations while using 34 personnel. Now let us talk about our coverage calls. The following is from Bill Belichick's 1985 NY Giants 34 defensive playbook. Notice how familiar the alignments are
Now that we understand Rita and Linda calls, we can take a closer look at our playbook art.
Well, as a madden player, that can look a little confusing. After all, that is how we play in real life, but not how we play in Madden. So, let's use MSPaint to flip all of this.
Ah, that's better. Now, let us take all of this complicated NFL jargon and explanations and try to simplify it for Madden:
4-3
3-4
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Yes, in summary, what I am telling you to do is to call this Cover 3 and Cover 1 plays a lot. Get really good at them. Understand your pre-snap assignments, make sure your players are aligned the best they can be against any given formation, be ready to flip or adjust the defense accordingly (Rita/Linda calls), and execute.
I personally like to stay in my base 4-3/3-4 defense even against 3WRs and just call Cover 3 Buzz:
4-3
3-4
This keeps the numbers in your favor with 7 in the box against a 6 man offensive alignment. You are also showing a pre-snap Middle of the Field Open (MoFO) look, which suggests Cover 2, but is really another cover three shell.
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Honestly, defense is a joke in Madden and any good offensive player online will rip you apart. I am darn good at defense on Madden and even I have a hard time containing the best players online. I just have to take risks, time my blitzes, and play as sharp as possible.
Offline, I tend to just play coach mode and not user control anyone after the snap. I like pretending I am the coach and once the ball is snapped, it is up to the team to execute. I try to draft and sign free agent talent that fits my scheme and auto-progress players. I take my lumps and move on to the next play and the next game when I lose. I know my scheme is sound, but the execution can be sloppy at times. Some of that is the AI, some of that is the individual player ratings. For example, the 49ers starting defense is brutal, while the back ups in pre-season games get destroyed at times. Ratings matter. Having talent matters. I like that. You can only scheme so much, eventually you need players to execute that scheme.