Measuring Defense

How come all the good stuff lately is coming from Detroit Tigers bloggers? First Billfer presents his data on working the count, then Brian Borawski does a great interview of Hall of Fame broadcaster Ernie Harwell, and now Lee Panas attempts to tackle one of the most troublesome aspects of baseball analysis, defense.

Panas’ method is simple but clever. Basically he takes several different fielding metrics currently in use and aggregates them into one measure. As Panas notes in his explanation of the method:

The benefit of this system is that if one of the measures doesn’t work for a particular player, that one “bad rank” will be tempered by ranks on other measures.

Panas breaks down the numbers, position by position. What I find interesting are the players where there is consensus across all systems, as well as those whose defensive skills appear to baffle the metrics. The latter group could prove helpful in identifying strengths and weaknesses of each, and potentially get us moving closer to a reliable system for evaluating defense in baseball.

Here are some of the players that intrigue me for various reasons.

 
These guys all finished in the top 10 in each of the four metrics examined. Most of them enjoy a stellar defensive reputation, so there are few surprises (Pedro Feliz being a notable exception).

How about the other end of the spectrum?

 
Above are all the players who ranked 20th or lower in all four metrics. No huge surprises here. Griffey used to be a Gold Glove caliber center fielder, but that was many years and many injuries ago. Weird to see Berroa here. I guess the Royals keep starting him because of his bat.

Now for the real fun:

 
This is the list of all players for whom the difference between their best and worst rankings is 20 slots or more. If you’re looking to poke holes in various defensive metrics, these guys are probably a good place to start. One thing that immediately jumps out at me is that the available systems appear to have trouble identifying good defenders at first base and shortstop. I wonder why that is?

Anyway, good stuff from Panas here. Start at the beginning and run through all the positions to see how your favorite players stack up against the rest. Maybe come up with some of your own ideas about how to refine defensive metrics. Hey, someone has to do it.