Also a QB who didn't have to step into his throws to make intermediate to deep passes would help the OL out a lot. Defenses know Alex can't make many throws so they stack the OL. if they run there are a bunch of defenders to stop it. If they pass they're not afraid to leave the Niners' WRs in single coverage deep.
Every once in a while this burns defenses (like Vernon did), but 9 times out of 10 it works out for 'em.
So you're looking for a QB who can get the ball out of his hands on the 2nd step of a 3 step drop? Smith is far from a good QB, but he's been sacked too many times this year before he even gets to set his feet.