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Wednesday, October 01, 2008

Preliminary 2008 Total Value Estimates

I've updated my total value estimates to include all regular season games played, assuming Hardball Times & ESPN have updated all of their sites through last night's game.

You can read about all the methods in this series of posts. I have some additional comments on the methods at the bottom of this post for those who are interested.

  • Total value estimates for every MLB position player, based on hitting (RAR; Runs Above Replacement level based on linear weights), fielding (Fielding), and their position (PosAdj). Units are runs produced above a replacement player.
  • Fielding measures are based on the average runs saved according to zone rating (ZR) and revised zone rating (RZR).
  • Pitchers are listed according to RAR (base runs saved above replacement) and FIP-Runs (a defense-independent pitching stat estimating runs saved above replacement).
  • League differences are taken into account. So are park differences.
  • Closers get a leverage-based bonus in value (though it's pretty rough).

I'll let you tour through the spreadsheet to see final player rankings. I'll submit a post in a few minutes with my picks for MVP, Cy Young, & Rookie of the Year.

A few additional comments for people interested in methods:

I say that these are preliminary, because there are a few additional adjustments I still have yet to do.

One, these are based on a base runs equation (for pitchers) and linear weights (for hitters) that are all based on 2003-2007 data. I'm going to calculate new equations that are optimized for 2004-2008 data one of these days. It won't make much difference, but the runs environment is decreasing in MLB and so it's worth doing.

Two, there is some discussion again about whether the most appropriate measure of chances for OOZ plays is innings played or balls in zone (BIZ). BIZ has always been a rather shaky estimate, but I've felt it was more likely to reflect the gb/fb tendencies of a given pitching staff. It may, however, confound the results, because it essentially measures chances in regions where OOZ plays were not possible. Innings is less likely to be biased, but is a bit coarser. I may make that change one of these days. This won't make much difference on a gross level, but it could conceivably make a big difference for some individual players with unusually high or low BIZ for their innings played.

One change I have made is that I'm now using the new position adjustment paradigm developed in this thread at Tango's blog. The net effect is to increase the value of skilled infielders (2b, 3b, & ss), and to decrease the value of the center fielders. CF's now have the same defensive value as 2B's & 3B's. C's also get a further boost in this design, whereas 1B's get knocked down a tad. This seems to be more reflective of the current state of thinking of how to rank the different positions than the old scheme. We're talking about a few runs over the course of the season, though, so this doesn't make a big difference.