"If one can get in then they should attend (or play). I believe a Mormon should commit their time and talents to building up the church, its members, it’s resources, it’s institutions, and all other related programs and affiliated memberships. This includes BYU."

No just because they get into byu doesn't mean they SHOULD go there. People can do missionary work at other schools. Help build the kingdom in other states other than utah. Its a personal decision about what is best for THEM. Who are you to say that every mormon that gets into byu should go there because it's their duty.

I agree on the fact that I believe that having good teams helps the church...but this is somebody's life...if its better for them to go to another school with better coaches so they can get into the NFL and have missionary opportunities IN THE NFL the why not?
I'm focusing on the missionary part since you did. There are other reasons why someone would maybe not go to byu. Whatever is better for them and their future.