I just wanted to pass along that I have tried adding few things to the MLB Salary Estimators for both position players and pitchers. Still, I cannot improve on the fit of either model. Here is what I have tried so far.
Defense: In the initial model I tried to include some of the more accessible measures of defensive ability, but nothing worked. So, after saying I wouldn’t do it earlier, I went out looking for UZRs (Ultimate Zone Rating). I tried several different measures of UZR and none of them had any impact on salaries. But, I’m not really surprised by this. Defense is so very hard to measure. And while UZR is the best thing that average fans has access to, I suspect the defensive methods used by MLB teams are much better….Or my model sucks.
Pitching: I tried two additions to the pitcher model; one worked and one didn’t. First, I tried controlling for the team of the player. The team should capture some park effects and quality of opponents, not to mention the thriftiness of the team owner. The fit of the model did improve, but the improvement was so small that it was not worth updating the estimator. Next, I tried to control for the park effects of all of the FIP components (K,BB,and HR). It didn’t help.
I would also like to address a common criticism that is misplaced. That is, several people have criticized the estimator because it does not account for part-time players. Well, there is a very simple correction. The model assumes the player gets 500 ABs in a season. If you want to look at a guy with 250, divide by 2.
Thanks for all of your thoughts and suggestions. Keep ’em coming!