Scrimmage every single week you aren't in the Cup and you can't care about the PG position basically. Each one plays the entire game each week and you'll train them just fine. You may want to start with Driving first for a few weeks at least since the trainee you have and the HoF guy both have piss poor Driving.
If I were you I'd toss Hendrikus though. He hasn't had much improvement, by the looks of it, and he'll be 20.