EA doesn't just deliver better running controls in Madden 17, there are also upgraded defense options that you will need to learn and utilize to your advantage.
A new Defensive Auto Flip feature will make sure your defenders are in the right place automatically to match the offense. You can turn this off or re-flip the play.
Each of the players on the field has a specific gap assignment. EA explains that, "e defenders now have AI and behaviors to execute the play called by the user and realize the intent of that decision, and these will be apparent to you both before and after the snap."
Essentially the play you call will dictate how your AI players respond better than in Madden 16. The players will use AI to react to changes at the line of scrimmage and fill another gap if needed. This is another area where ratings come into play. A player with a slow Player Recognition Rating will be slow to react, while one with a high rating will adapt quicker and deliver better results.