That disconnect has always been a huge problem with me. Something is practiced in the spring, shown in the spring game, practiced in fall camp and talked about during the pre-season as a 'this is what we want to do.' The season hits and it doesn't work.
If something doesn't work in live action then there's obviously a problem in preparation and/or behind the scenes and that's incredibly aggravating. I think play calling is certainly an issue from time to time, but I also think the players just aren't doing what's being asked of them. Who is to blame? I always look to the coaches first because if Player A is struggling to get separation on his routes and make plays, you either need to find better ways to involve him or find a player who can do what you want.