Is Zimmerman a Better Fielder than Longoria?

Like many wannabe saberdorks, I love Joe Posnanski’s work. It’s not just because he’s so much better than, say, [horrible-and-inexplicably-award-winning columnist for major newspaper] or [rumor-mongering baseball reporter prone to bouts of self-righteousness]. This isn’t a Posnanski tribute, but in short: Posnanski is great because he tells an engaging story and incorporates good baseball analysis without confusing one for the other.

This doesn’t mean that I always agree with Poz.* I disagree with many things written by sportswriters. In Posnanski’s case, I think highly enough of him that it’s worth quibbling over minor points, unlike, say, with [arrogant breaker of stories for your dad’s favorite sports magazine that we would have found out about anyway], who is only worth refuting because of his [alleged] influence. I hold Posnanski to a higher standard (not that he knows I exist).

*Or “JoPo”; has a sports journalist ever had so many different nicknames?

Which brings us to today’s Poz post on likely future Hall-of-Famers currently under 30. It’s an entertaining (if unsurprising) read. One claim in particular caught my eye. Posnanski writes that Ryan Zimmerman is “probably better defensively” than Evan Longoria. Now, Longoria didn’t qualify for the list (hasn’t played 500 major-league games), so while I do think he is the better player, that isn’t the point here. The issue is whether Zimmerman is “probably better defensively” than Longoria, as Posnanski claims.

Although he doesn’t cite specific defensive numbers in this piece, Posnanski has used Dewan’s plus/minus system in the past (although he has increasingly cited UZR). Here are the Dewan numbers for Zimmerman and Longoria in seasons in which they’ve both played (2008 and 2009):

Plus/Minus 2008:
Zimmerman: +10 plays (+11 runs) in 910.2 innings
Longoria: +11 plays (+9 runs) in 1045.2 innings

Plus/Minus 2009:
Zimmerman: +28 (+22 runs) in 1337.2 innings
Longoria: +21 (+17 runs) in 1302.2 innings

Over the last two seasons, Zimmerman has been 7 runs better in about 100 fewer innings according to plus/minus. Seven runs is seven runs, but given everything that is rightly said about the large error bars on defensive metrics, the gap isn’t as significant as it looks.

Given the various issues with defensive metrics, looking at other systems will give us a more perspicuous overview. Here at FanGraphs, UZR is used to measure fielding. I’m not qualified to argue which metric is the best; I’m simply using them as separate data points. UZR has a helpful “rate stat” version, UZR/150 (runs above/below average per 150 games). I’ve included the “non-rate” runs in parentheses.

UZR/150 2008:
Zimmerman: +3.4 (+2.1)
Longoria: +20.1 (18.5)

UZR/150 2009:
Zimmerman: +20.1 (+18.1)
Longoria: +19.2 (+14.9)

Suddenly things are less obvious. While 2009 was practically even, in 2008 UZR has Longoria almost two wins better. Their career UZR/150s: +12 for Zimmerman, +19.6 for Longoria. It’s a smaller sample for Longoria, but if you check Jeff Zimmerman’s regressed and age-adjusted 2010 UZR/150 projections, Zimmerman is at +10, and Longoria +12.

Defensive stats are obviously important, but when estimating fielding skill, in particular, we need to weight visual evidence — scouting — heavily. I’m not a professional scout, and unlike Posnanski, I don’t have access to them. Perhaps legendary scout Art Stewart, who told Poz “You will remember this day for the rest of your life” after Royals great Chris Lubanski’s first batting session at Kauffman Stadium, thinks Zimmerman is way better than Longoria. Jokes aside, scouting is essential for estimating defensive ability.

While most of us don’t have access to professional scouts, we do have access to the
Fans Scouting Report. In both 2008 and 2009 Longoria was rated as (slightly) better than Zimmerman.

Given that plus/minus seems to “prefer” Zimmerman — and UZR, Longoria — does this make the Fans Scouting Report a tiebreaker in Longoria’s favor? No. Given the relative closeness of the rating, neither the numbers nor the testimony of observers has the degree of reliability for us to make that kind of call. However, contra Posnanski, I do not think we can say that either player is “probably better defensively” than the other.

Molehill converted to mountain? Check. Happy American Thanksgiving, everyone!