Missing in this "only 6 Quarters" stuff is the 12 preseason games he's played in. You can't fail but to make a performance chart out of those games, grading it from his rookie year. Since, BB rarely gives the backup QBs front line talent to work with, you can should be able to make a lot quality inferences from those games. Then compare those inferences to the actual "6 Quarters" and, IMO, you have enough information on whether (and by how much) he has improved since his first preseason game and whether those "only 6 Quarters" are a real showcase.
Garappolo is not Hoyer-Cassel and referencing them is changing the subject. Let's stick to Garappolo.