TYA reader Andy sent us the following question recently: “When I went to Fangraphs I was surprised to see Curtis Granderson and Robinson Cano ranked very low in fielding. That is counter intuitive. Could you explain?” Ironically, a flurry of posts in the Yankee blogosphere directly addressed Curtis in the field, and whether or not defensive metrics rate him poorly because Brett Gardner runs down so many flies that a center fielder would normally catch. This RAB post contains links to many of the recent articles on this subject. I, however, would like to take my response in a more technical direction, not the least so I can include Robbie, but also to shed light in general on the shortcomings of many of the defensive metrics that are used.
Fangraphs may call the fielding metric they place on their core player card fielding, but if you dig a little deeper you’ll find that this is actually UZR. The short answer to Andy’s question is therefore that UZR may be a highly respected metric, but it is also flawed. Fangraphs doesn’t hide from this, and if you have some time a detailed article about the site’s UZR metric may be found here, but I’ll do my best to summarize, before I hone in on my objections to the metric and specifically why it harms certain Yankee fielders.
In short, UZR, or Ultimate Zone Rating, tries to rate a player’s fielding using linear weights, in a fashion similar to how wOBA tries to rate a players offense. The metric is calculated in terms of runs saved (a positive score) or not saved (a negative). Other definitions that I’ve read spoke of cutting the playing field up into a number of zones, but Fangraphs didn’t list that so I’ll assume they don’t do it. Instead, they try to determine how difficult a play was to make, who on the field would normally make the play, and score its outcome accordingly, rewarding a player for a difficult play and penalizing him for, say, botching an easy one. The basic concept was to address the fact that a player with poor range might not make a lot of errors, but could actually be hurting his team because he lets balls get by him for hits that a better fielder would scoop up.
The problems with UZR have to do with how hits are defined, and which ones are measured. According to the Fangraphs article, “The types of batted balls that UZR processes are ground balls, bunt ground balls, outfield line drives, and outfield fly balls (including so-called pop flies). All batted balls are put in one of those categories. No other batted ball type distinctions are used, such as “fliners,” which are used in Dewan’s plus/minus system.” Also from the Fangraphs article, “Finally, line drives and pop flies that are less than 180 feet from home plate are ignored.” This means that UZR ignores just about anything that an infielder catches in the air. (On a final note, while I could not find evidence of this in the article, it has also been my understanding for some time that UZR ignores anything caught in foul territory.)
Right away it should be clear why Robinson Cano, and also Mark Teixeira, don’t get a lot of love from UZR. It ignores plays they are very good at. (In the case of Tex it doesn’t put a lot of value on scoops made on throws in the dirt to the first baseman.) Obviously data are lacking, but anecdotally Robbie has incredible range on pop flies hit somewhere between the infield and the outfield, and he makes a lot of these catches. UZR ignores these plays as either luck, difficult to classify, or a case of ball-hogging, where one player makes a play that a different fielder really could have, and should have, made. UZR also ignores infield line drives as luck.
Fundamentally, this classification of infield hits is difficult to accept. Both Cano and Tex make so many tough catches on fly balls that no one else can get to that it is difficult to dismiss these plays as luck, or anything else. UZR is therefore a statistic that focuses heavily on how well infielders vacuum up grounders, but almost nothing else, which is to say that it looks at what most infielders do well, but conspicuously ignores what almost the entire Yankee infield does well. In light of this, UZR is not a statistic that Robbie or Tex would ever score well in. The eye test suggests that neither has great horizontal range at his position compared to say, Dustin Pedroia or Doug Mientkiewicz, but it also shows that there is more than just horizontal range to playing their positions, but UZR doesn’t consider these skills.
Curtis Granderson is a different animal, but I have a hypothesis as to why UZR penalizes him also and, yes, it’s because of Brett Gardner. UZR rewards a player for making a difficult catch, and it is meant to be scaled against everyone else in the league so that if you summed it up for all players the total would be zero, or close to it due to rounding errors. UZR also tries not to penalize a player if he doesn’t make a catch that someone at his position normally would because someone else, say a speedy left fielder with ludicrous range, made the play. However, if the left fielder with range is catching a fair number of balls that the center fielder normally shags, odds are he’s catching the more difficult plays for the center fielder. The center fielder, in turn, is left to field fewer plays in total, and more of the easy ones. Both of these things will contribute to a negative UZR if the statistic is scaled against everyone else in the league to sum to zero.
My hypothesis is that this is what is happening with Curtis. According to many of the articles the RAB post linked to above, Garnder’s range in the outfield allows the Yankees to play Granderson well into right center. If Gardner gets to more of the difficult plays hit to Yankee Stadium’s death valley, while Curtis is left fielding easier plays for the center fielder and plays that a right fielder would make more frequently then Curtis will wind up with a lower raw UZR score. That raw score may not be negative, but it can quickly become negative once it is scaled against the rest of the league.
I have a few additional points about UZR and defensive metrics that are also important. First, UZR is not as robust a statistic as other measures. According to the Fangraphs article, one season of OPS data is as robust as two seasons of UZR data. This means that it is difficult to infer much about how a player has fielded with only a single season of UZR data. It has been suggested to me that a better way to use the stat to judge someone in the field is to see whether or not the player has a positive or negative career score, as this is a more robust sample of data.
Finally, just as there is no agreement on how to calculate WAR between the major stats providers, only agreement that WAR is the right way to go conceptually, there is no agreement between which defensive statistic is best, or how to calculate them, just that fielding percentage and errors aren’t going to cut it. One need look no further than Fangraphs and Baseball Reference for evidence. Entering Tuesday’s game, Fangraphs rated Granderson -9.2 in fielding, while BRef had him at -0.6. Neither stat rates him well this season (but both have him plus for his career), but they also don’t agree on how valuable he has been in the field, which makes it difficult to accept either at face value.
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