Yet Another Causal Confusion

This one is more subtle. As the baseball season is set to begin, a lot of attention is being paid to Joba Chamberlain's possible roles on the Yankees. He will either serve as the principle set-up man or as a starter. Yahoo sports published an article today by baseball "Economist" Vince Gennaro. Vince did some research:

I recently applied statistical analysis to the more than 70 free-agent signings over the last four months. In doing so, I was able to estimate the going rate for pitchers based on both their role – starter, middle reliever, closer – and their level of performance, measured by win shares from “Hardball Times.

And he discovered, to the surprise of no one, that number one starter get paid more than number 2 starters, that closers make more than set up men, etc.. The problem here is that these values are associations. A pitcher's role is strongly co-linear with his talent. Set up men are cheap because in general they are not that good. It is not entirely clear what it would cost for a lights-out set up man. It could be a lot.