If we had, say, a top-14 defense that forced turnovers and punts giving us good field position, we'd be putting up more points. There's a reason we possess the ball for 29 minutes per game; Fitz and the offense are forced into long drives from poor field position. We're not forcing fumbles in the opponent's half.
If this were an average defense, Fitz wouldn't be in the position he's in at the end of most games. Yes, he's not elite, and the opposite of clutch, but posters would have a very different opinion of him if we had a defense that could put us in a position to score easy points and control the game.