Hearing some of the claims in this thread got me interested in looking up how the Steelers have done with and without Polamalu over the last few years. I want to take a look at a couple different breakdowns still but here is what I've found thus far since the 2006 season:
W % with Troy: .661
W % w/out Troy: .571
Strength of schedule with Troy: .509
Strength of schedule w/out Troy: .446
Avg PPG allowed with Troy: 16.9
Avg PPG allowed w/out Troy: 17.3
Median PPG allowed with Troy: 17
Median PPG allowed w/out Troy: 20
Avg Opponent offensive PPG with Troy: 21.1
Avg Opponent offensive PPG w/out Troy: 20.6
The final statistic looks at the average amount scored by the Steelers opponent from that season. I took all these numbers and averaged them to see if the Steelers were facing stronger offenses in one set of games or another.
The Steelers have done significantly better with Polamalu in the lineup against a tougher schedule. Seeing that I expected there to be a larger disparity between the average PPG allowed statistics or at least that the offenses they were facing would be much better. The median PPG allowed statistics are however more along the lines of what I expected.
So while the Steelers have done noticeably better with Polamalu my data doesn't necessarily confirm it's him causing the defense to improve. His leadership could very well be a significant cause for the difference in team performance or the difference could be random.
The data seems more in line with my memory if I just look at the past two seasons. Over that time the Steelers are just 6-7 without Polamalu and give up 21.5 points per game whereas they are 15-4 with him giving up only 14.5 points per game.
That said, I do agree that Polamalu is overrated. He was NOT the best defensive player in the league last year. Both Clay Matthews and Tramon Williams had better years last year and that was just on the Packers defense. Polamalu is however a great player. Calling him anything but great is far too harsh.
Born and bred a cheesehead