I see what you meant by good arm. From my own experience when someone says they have a good arm it is referring to throwing (or pitching if baseball) strength, how far they can chuck a football, not how accurate they are.
Locker does need to work on his accuracy and touch (he devoted the off season to working on his intermediate passing), but his 47% completion percent wasn't entirely his fault. Our dawgs also had some inept wide receivers last year (all graduated) that dropped a lot of his passes.
He was only a freshman last year and his accuracy improved as the year went on, so I think each year he will get better and develop more touch. It is because he has such a powerful arm (was a baseball draft pick, 90+ mph fast ball, WA state player of the year in football & baseball) that he has below-average touch (that and his HS team ran a wing-t offense).