What the Hell is a "System QB" and why is it bad to be one?

[vailpass]

Originally Posted by Brock

Montana won many, many games on the strength of his ability. There is a lot more to being a quarterback than how far you can throw a ball.

You can be a Montana fan and still acknowledge he was a system QB, probably the best system QB to ever play the game.
Do you think Montana would have won as many games as Favre or Elway if he had played on the teams either of those had; teams that required the QB to carry the game in many of their seasons?

BTW, I'm not saying 'system QB' is a negative, I don't think it is at all. I consider the term to mean the QB has mastered the offense and runs it at top capacity.