I really feel you on this. I am no programmer but I think this could be greatly improved by just adding a user "engage" button, maybe the left trigger on the controller. If the user had an option to engage a player or not, so would the AI and this would allow for more realistic animation variation. For example, win/lose/tie animations for an offensive player engaging but the defender not engaging, trying to block shed (ie. defenders trying to get to the QB/ball carrier), win/lose/tie animations for a defender engaging but the offensive player not engaging, trying to shed contact (ie. OL getting out for screen passes, WR/TE getting off the LOS and finally defensive holding would exist) and win/lose/tie animations for both offensive player and defender engaging (ie. defender trying to hold the point or trying to push the offensive player back into the back field and a offensive player trying to pass protect or run block).