I'll go back to the original question: "Why so much faith in J.P?"
Because Mularkey, Clements, Wyche clearly supported the change. All 3 of which have coached many NFL QB's in their time. Especially Wyche, who coached Montana and Esiason.
If they feel confident that J.P. is ready to start, I will trust their opinion way before a worrywart fan.
That bein said, its still the NFL and he still may not pan out....