So I’m doing a routine stat search on fangraphs.com for some data on outfield defense, and I happen to notice that one of my favorite Tiger players is atop the leaderboard. I checked my search criteria- 2013- American League- Outfielders- Qualified. Yep, that’s right. Sort by UZR/ 150, and it’s- Andy Dirks, with a plus 32.9.
Now, if you’re not familiar with advanced defensive metrics, UZR stands for "Ultimate Zone Rating" and the UZR/ 150 is supposed to tell us how many runs a player would save, or cost his team over the course of 150 games as compared to the average fielder at the same position.
UZR takes into account all sorts of things. A full primer is here in the fangraphs glossary.
Basically, they use real play by play data recorded by Baseball Info Solutions (BIS) regarding the zone that a ball is hit to, the speed and trajectory of the hit, and whether an out was recorded by the fielder. They add, or subtract, points for errors, and assign values for arm strength for outfielders and double play values for infielders.
UZR is the defensive version of runs created. The runs are not actual runs saved, but by taking each play made by a fielder and plugging it into the average baseball situations, it gives us a number that should measure the value of the fielder's performance in terms of runs. It's the defensive component of WAR (Wins above replacement). In my view, it's the weakest link in WAR.
Anyway, there on top of the list is our own Andy Dirks, not exactly known for his defensive work, rated number one among all outfielders in both UZR at 9.7, and UZR/ 150 at 32.9. So I decide to resort the data by all fielders, and Dirks is still on top of the chart in UZR/ 150, although the Orioles’ Manny Machado is on top of the UZR list with a plus 14.6.
Now, any Tiger fan who has been watching Machado playing in the current series and the recent series against the Tigers can see that the kid is something special in the field.
Next, I look over to the other popular defensive metric, which is Defensive runs saved (DRS). This is the creation of Bill James, author of "The Fielding Bible". And there on top of the charts is- Andy Dirks, with a DRS of plus 10 runs. That’s pretty close to the UZR calculation of 9.7 runs saved. And once again, he is second in the league among all fielders to Machado. Coincidence?
Now, if you know anything at all about UZR, or if you read the conclusion to the linked story that I posted above from the fangraphs’ glossary, then you know that small samples with defensive metrics can be extremely unreliable. Ideally, you have two seasons’ worth of data, or at least one season where all the data seems to be telling you basically the same thing.
I have a preference for UZR/ 150 over UZR because it evens out the amount of time that a player is on the field. Despite his brilliant glove work, Dirks is not in the starting lineup every day like Machado. In fact, when the Tigers start a right handed hitter in left field, they’re more likely to use the great Don Kelly as a defensive replacement than Dirks.
When we’re dealing with smaller samples, such as we are just over 65 games into the season, I would not take these defensive metrics too seriously. In fact, I still like to look at stats such as Revised Zone Rating (RZR) and the number of Out of Zone (OOZ) plays to get an idea of a fielder’s efficiency.
RZR measures the percentage of plays that are hit into a given zone at the position, and provides the percentage of those that are turned into outs. A ball is credited with being in the zone if 50% or more fielders at that position make a play on the ball. The accuracy of the zone and whether a play is made is very accurate.
What is not accurate about RZR is that there is still a chance that one player at a given position might have a disproportionate number of balls hit harder, or hit to the far edge of the zone, whereas another player might have more balls hit right at him. It doesn’t adjust for defensive shifts, and as with all statistics, that randomness will even out over a large sample of data.
Over a full season’s worth of data, you can get a pretty accurate idea of how efficient a player is within his zone using RZR. it's even good for range up to the median range point of players at that position.
Out of zone plays are not a percentage, but rather just a raw number of plays that a given player makes outside of that calculated zone. Every player makes at least some OOZ plays. For example, Jhonny Peralta is a player who is very reliable within his zone, but has limited range when tested. Sure enough, he led the league last year in RZR, and was dead last in OOZ among qualified shortstops in the American league.
A look at the RZR ratings for outfielders so far this season is a good news/ bad news scenario for Tiger fans. Dirks is eighth in the league with an RZR of .939. So he records an out 94% of the time within a zone where half of all outfielders make the same play. Some of the ones he does not make could be due to positioning, but again, that will even out over time.
The bad news is that Torii Hunter is dead last, 31st out of 31 on the list, with an RZR of .819. Now, I’ve watched Hunter for the past several years living out here in Orange County, and I have no doubt that he has lost a couple of steps this year. I think he is playing deeper than he did in Anaheim, and that could be due to the change in parks, or due to the change in his body. Magglio Ordonez played deeper and deeper each season toward the end of his career. Hunter ranked fourth in UZR in 2012, fifth in DRS, 20th in RZR, and tenth in OOZ plays.
Checking on OOZ, Hunter is 20th and Dirks is 27th of 31 qualified outfielders. I can believe that. Neither one has made a lot of spectacular plays that I’ve seen. Dirks would rank higher on this list if he played every game.
Before I leave the page, I’ve got to see how the other Tiger outfielder is doing. Austin Jackson, I happen to recall, was among the league leaders defensively in 2012. He was eighth in RZR, third in OOZ plays, twelfth in DRS, and UZR/ 150. That is among 32 "qualified" outfielders.
This season, Jackson has missed a month on the disabled list, so he doesn’t have enough innings to be qualified. I reset the innings to 300 (he has played 340) and now he’s on the list. Jackson ranks 44th of 47 outfielders with a negative 22.7 UZR/ 150. His UZR is minus 4.9, meaning he is five runs below the average outfielder, and minus 4 DRS. In OOZ, he is dead last with just 15 out of zone plays.
At this point, I’m in complete disbelief with respect to any of these numbers. Okay, Jackson has missed a month, so he’s not going to make as many plays as a guy who has played 200 more innings. But he doesn’t look like a below average outfielder to me. Well, with 95 games or so left to play, he can make up those four or five runs and then some, and I fully expect he will.
For what it’s worth, Andy Dirks has not committed an error in the outfield this year, so his fielding percentage is 1.000. If you find fielding percentage to be reliable, that makes one of us.
And thus concludes my venture into the small sample of defensive metrics after only 65 games this season. I’m very happy to see Andy Dirks on top of the list of outfielders in the American League. But I take it with a grain of salt. I thought it would make a better headline, and a better story than just writing about advanced defensive metrics.
So much for small samples. And so much for defensive metrics. For now.
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