Has Warren Buffett’s Management Style Goosed Returns?

I've been reading The Warren Buffett CEO and there was an interesting chart about the yearly returns for Buffett, Peter Lynch, and Lou Simpson. I uploaded the data to Swivel (YouTube for data, as they call it) to play with the graphs, and something interesting struck me. Look at the graph below.

Buffett vs. S&P500

The one thing that has always nagged at me is whether or not Buffett's performance is statistically significant. I mean, someone has to be the best investor of all time by definition. While I agree he is sharp and his methods work, in general he has followed the market, but eked out larger gains.

Reading the book, many of the managers talk about how they love working for him and being a part of Berkshire. They have access to all the capital they need, Buffett doesn't bother them, they don't have analysts or press to deal with, they don't have to meet quarterly earnings goals, and they can focus on the long term. So what I am wondering… is it that – Buffett's management style – that has led to the extra gains?

Think of it this way. Buffett is a great investor, but so are a handful of other people. Is the thing that sets him apart, even above the other great investors, a few extra percentage points of return due to the freedom given to his managers? I don't know. I'm not saying yes or no. I'm just wondering what the rest of you think about it.