I would bet that McVay felt that he could fix Stafford's risk taking by putting him in better situations and giving him more options that he was just accepting that those bad decisions are part of the package.
I actually agree that Stafford is much like Favre but I don't consider that such a good thing when it comes to traits. I like aggressive. I don't like aggressive regardless of circumstance. Favre and Stafford fall into that category. There is a time to just kick the FG and a time to go for it.
Favre and Stafford seem to always go for it when prudence is sometimes appropriate. Let's remember, Favre had some real high points but in 20 years in the league, won 1 SB. Which I wouldn't turn down of course but that style of play does not suggest a good shot at a championship.