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March 4, 2003

Breaking Balls

Getting Defensive: The Basics

by Derek Zumsteg

The basic problem with trying to evaluate fielding performance is that it's too complicated.

The greatest change in baseball thought over the past 20 years has been the shift of focus from one offensive statistic (number of hits / number of times to plate that did not result in a walk) to a better one (number of times reached base / number of times at the plate). Granted, I realize that I'm omitting sacrifice flies and catcher interferences there, but that's the essence of batting average and on-base percentage. If you only knew on-base percentage, you'd do pretty well comparing players.

Unfortunately, there is no easy way to do this with fielding statistics--a fact that results in a disagreement between our eyes, instincts, and what we read. I've been trying to educate myself on fielding statistics for the last couple years, and I want to admit up front that I have not been able to reconcile them with my own evaluation. When I see Mike Cameron rated as a slightly above-average center fielder last year, I roll my eyes, because I have in my head a mental image of how far he can go to get a ball--a massive expanse few visiting outfielders can cover. The issue, though, is that it's not an accurate picture or particularly useful in evaluation.

The first unit of mainstream fielding evaluation is the error. A player gets an error when he makes an obvious gaffe that results in a runner advancing. With this knowledge, raw errors can be compared: Orlando Cabrera led the major league shortstops last year with 29 errors, while Mike Bordick only made one.

That said, there are a few obvious problems with errors. First, they are the subjective judgment of the official scorer of that game. For an error to awarded, the scorer must believe that an ordinary effort would have gotten the runner out (or not allowed the runner the extra base). Hitters want to be credited for hits, while fielders don't want to be marked with errors. This has led to direct lobbying of scorers by players and teams on decisions, and because the scorer is team-employed rather than a member of the umpiring crew, there's a bias, conscious or not. It also requires the scorer make an evaluation on what an average player at that position would have done. If you're a home-town scorer for a bad shortstop, half the plays by a shortstop you see are going to be that bad shortstop; he's going to change the average you're scoring against, no matter how you resist--it's the nature of perception.

Second, it's a counting statistic, like home runs. Boston's Lou Merloni played an inning in left and made no errors. Does that mean he was a better left fielder than Jacque Jones, who made five errors while playing regularly all season. Hell no.