If you still think that TS is a better QB than JM going into this season, then you are essentially second guessing CNS's decision after USF. A decision made after an extended QB competition running through the first three games of the regular season. In my view, that's a very arrogant stance to take considering that you really have are basing your opinion on a fraction of the information that is available to CNS.
You asked whether erratic snaps impact the QB. Here's CNS's answer:
“And he was snapping the ball early sometimes and when we weren’t ready sometimes. That’s a huge issue for our quarterback.â€Â
Link
You asked whether protection impacts the QB. Here's CNS's answer:
"Once your quarterback starts getting affected a bit even though its not necessarily his fault completely, it's tough to play," Saban told McAfee. "We got to the point in the game where we didn't have a lot of confidence in being able to throw the ball, not because of our skill guys, but because of our inability to protect."
Link
FWIW, I didn't start off being "petulant" -- but when you have the same uninformed response from 20 different people, none of which are providing any support for what they are saying, it gets extremally frustrating.