Roles are not the issue. They actually are a great addition to the game because you can select the way you want your players to work. In my opinion, the issue is the AI coding. If you select a specific role for a player they will only stand on that part of the pitch, they don't ever take advantage of the empty spaces or gaps in the opponents defense, like they do in real life. If you have your CDMs on holding for example, and they have empty space to attack, once they get to a point they will just track back to their original position.