Here's a fun little factoid for Twitch.
Since Jay Cutler came into the league, which NFL quarterback has the best winning percentage when the defense holds its opponents to 23 points or less? The answer: Jay Cutler, who has won 92.3% of his games when the defense allows 23 points or less. And we're not talking about 7 points or less or something like that here, 23 is a fairly sizeable number for a stat like this, and to win 92.3% of the games under that number is pretty remarkable. It's not Cutler's fault that he plays for one of the few teams in the league that is more likely to allow 30+ points than they are to allow less than 20.
You're right in saying that the quarterback is the most important position on the field, but it's still only 1 position and you give it way, way too much credit. As others have posted, the other teams with defenses that gave up as many points as Denver's were winning 2 and 3 games a year, not 7 and 8 like Denver won. Cutler's 15-17 record the last two years is NOT a mark against him, it's a testament to how good the offense he's lead has been considering that other teams with defenses that bad have records closer to 5-27 over that span.
Kerry Collins is a good example of where your theory DOESN'T work, so I'm not sure why you keep bringing him up. When he is surrounded by bad players, they lose miserably. When he is surrounded by great players, they do well. That doesn't make him a winner, that makes him a roleplayer.
Also, for the love of all that is holy please stop bringing up whether or not people were a "winner" in college. You're only embarrassing yourself with that point. The list of "winners" in college that ended up being flops in the pro's is 10 times the size of those that went on to become successful.