You are completely exaggerating! Manning's 1st season was very bad, I will give you that. He threw 26 TDs, but also 28 INTs with 575 attempts. But after that Manning improved. Statistically, it does look like Manning stepped up to another level once Caldwell got there, but he WAS NOT an interception machine before Caldwell.
I think that Caldwell helped him, but Manning was going to be one of the better QBs in the league regardless. Caldwell just might've helped him improve to be one of the best. There's NO WAY that Caldwell "made" Manning.
I think it's stupid to say that Caldwell and Lombardi won't be able to help Stafford improve (it remains to be seen how much), but at the same time you're making it seem like Caldwell was the best QB coach in the history of the NFL!