Last season's roster and this year's are different in terms of the QB depth chart. Last year we had Malik in his 4th year, Evan (who's not remotely a division 1 QB) and two true freshman in Weldon and Perry (who got here in late May). Of course we weren't going to do any better that year than with Malik.
The problem with the improvements you're citing is that as a 5th year senior, you're highly unlikely as a QB to make a tremendous leap in improvement on accuracy, learning how to make reads, etc.. It's also rather difficult to fix complacency, which Rosier admittingly was last season.