Mitt is in 1AA for gods sakes.
If he's gotten that far then I don't understand how he's struggling ?
Gameplanning skill comes last IMO. You do not start to realize the importance of gameplanning until you are at a level of competition that makes it apparent, or at least that was my personal experience. I am just now starting to understand good game planning, which is probably why I respond to questions like this one.
Also...there is no real documentation out there talking about how to gameplan. You usually find the information by trial and experience or find a coach willing to teach you. lyonz taught me a bit and pete. They didn't hand it to me, but put me on a path to understanding. I simply cannot thank them enough for taking this game to a higher level of enjoyment.
By the way, I am not talking about basic gameplanning (set your lineup, depth charts and a basic gameplan). Gameplanning is detailed plans to use your strengths against an opponents weakness. I am still a novice in this area in all honesty.