All I care about is that the Vikings are better off with him than without him (in my opinion). He does not have to take the whole game on his shoulders (like he did in NY and with GB the last few years he was there). All he needs to do is be able to hand the ball off to AP a bunch and throw to single covered receivers 15-20 times a game. I think he can do that just fine. He gets in trouble when he tries to make too much happen. Not to mention he is throwing under a system he is very familiar with. I think he is much better the Vikes current crop of loser QB's even if he is old and not what he was. Even if he gets hurt or just can not play any more they still have the same options to replace him. Would I rather have a young star QB with 10 years of play left in him? Yes. Am I happy the Favre joined? Absolutely.
Anyhow, I really like the Vikings chances this year, great offensive and defensive lines, the best RB in the league, a veteran QB to hit a group of pretty speedy WRs. Secondary is not great but is probably better than average. But it is silly to speculate now, that is why they play the games. But if they only win 8 games and miss the playoffs with Favre, I doubt they would make the playoffs without him.