Excuse this quick media rant:
What makes a player good defender? If you’re following some Braves broadcasters and writers, you’d think it’s a lack of errors, and little else.
For many years, defensive statistics were so limited that they were meaningless. We had errors, along with putouts and assists, but these have very little meaning in the scheme of things. Errors are just a small, scoring-subjective part of defense, and today’s good defensive metrics treat them as such.
What’s really important on defense is actually pretty intuitive if you’ve watched much baseball: range, glove-work, and arm strength. Can a guy get to a lot of balls? Can he field them when he gets there? Can he throw out or hold a runner with his arm? These things are measured by modern systems like UZR (Ultimate Zone Rating), which divided the field up into “zones” and determines how many plays a player makes compared to other players in that zone, adding on errors and arm ratings to the end. It’s much more sophisticated than that, but you get the idea.
The player in question today is Casey Kotchman, whose defense was the subject of an article last night by MLB.com’s Adam Rosenberg. Remarkably, Kotchman has not committed an error as an Atlanta Brave in nearly a full season’s work. But how does Kotchman really stack up to other NL first basemen?
UZR represents each player’s fielding run contribution for the season, and UZR/150 makes it a rate stat, normalized to 150 games.
As you can see, Kotchman performs well, but he’s not clearly the best, even though he is the only player among qualifiers who hasn’t committed an error. He’s basically in the same category as Howard and Lee: the former has superior range, and the latter profiles as a more balanced defender (like Casey). Also notable is that Albert Pujols falls in the middle of the pack, despite his billing as a top-notch defender. Perhaps he would be one if he were completely healthy, but the same could be said of other players on the list.
Of course, Howard, Lee, and Pujols are much better hitters than Kotchman is, but that’s not really the point here.