The OP's question was hypothetical, the sheer stupidity of the question was not
I think the question is a great one considering we lost several games last year when he panicked within a collapsing pocket. How would Kaaya have held up in full contact vs. our front 7? Let's look at how he did against pressure.
FSU: 19/32 | 59% completion | 6.7 Yards per catch | 2 TD | 1 Int
UNC: 16/31 | 52% completion | 7.2 yards per catch | 0 TD | 0 Int
VT: 23/38 | 61% completion | 8.5 yards per catch | 2 TD | 1 Int
ND: 26/42 | 62% completion | 6.9 yards per catch | 1 TD | 1 Int
Turns out he was pretty darn mediocre. Could he throw it on a rope and nail Njoku running in full stride once a game? ... yep. But go back and look at his stats for the tougher games. Most of his completions were high percentage passes to the WR screen or short slant and wheel routes. He averaged 6/7 yards a catch in 3 of those losses even with breakout YACs from Richards, Coley and Njoku.
The stats also don't show how inconsistent he was. For most of the FSU game, and over half of the Va Tech, UNC and ND games, Kaaya couldn't hit the state of Georgia if he was standing on the FL/GA state line. Even in the bowl game for the first quarter and a half, Kaaya was extremely shaky, and was bailed out by amazing play from Richards and Njoku.
I think all of us can agree that Rosier and Shirreffs won't come close to Brad's passing accuracy when he was protected and had a hot hand. But I am interested to see if they'll perform as well in game situations, given the added dimension they bring with being able to move with a moving pocket or scramble if the pocket breaks down. That compensates for a lot but is hard to measure.