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Feb 252010

Derek Jeter’s UZR at shortstop last season was 6.6 runs above average. Nick Swisher’s UZR in right field last season was -0.7 runs below average. Johnny Damon’s UZR in left field last season was -9.2 runs below average. From my own experiences, many baseball fans often toss around FanGraphs’ Ultimate Zone Ratings without much context or detail, citing UZR similarly to the way in which I have done just prior to this sentence, as if the numbers provide all that is needed in order to fully understand a player’s defensive impact on a given season. However, for those who rely upon FanGraphs for their UZR figures (most of us, it seems), it is very important to remember that each player’s rating can be broken down further into three distinct parts.

For outfielders, the three-pronged rating is the final sum of a player’s range runs (RngR), error runs (ErrR), and arm runs (ARM), whereas for infielders, a player’s UZR is based on on range runs and error runs, however, arm runs are actually replaced by double play runs (DPR). Each of the three values, together, amount to a respective Ultimate Zone Rating. The problem, though, is that sometimes, ratings are cited at large, with writers employing FanGraphs’ UZR system and citing an UZR without added delineation that might provide greater insights as to why a player’s rating is as high, low, or average as it is. In reality, an UZR can occasionally be the product of just one of the three elements which are used to comprise it, making matters more than confusing when evaluating a player’s overall defensive value in a given year. For instance, an extremely high ErrR can skew an infielder’s UZR, masking tangible range issues. However, if the error score is not expounded upon, defensive weaknesses may go unnoticed.

This is an issue I often deal with when discussing a player’s Ultimate Zone Rating. In order to address it, I tend to rehash much of what I said above, but in an abbreviated form. For practical purposes – and for some nerdish fun – I thought perhaps I could try something different, and hopefully more interesting, to help readers understand what an UZR really “means” when it is attached to a player. Hence, the UZR Chart is born (I guess DiamondView inspired me). I have opted to represent the three defensive components of a player’s UZR using a simple bar chart. The bar chart seemed like a good idea because it allows for negative numbers and creates a rather straightforward visual comparison. Also, it allows us to visually perceive the way in which a player’s UZR, which I have also decided to include in each UZR Chart, can sometimes be heavily determined by one of the three defensive elements – RngR, ErrR, ARM/DP – discussed. Basically, via chart, we can eyeball a high or low UZR score relative to a high or low RngR, etc.

An example of this is the figure to the right, which is an UZR Chart documenting the defensive abilities of Houston Astros outfielder, Hunter Pence, in 2009. I chose to chart Pence, a non-Yankee, as the first illustration, mainly because of his interesting UZR. Last season, Pence’s Ultimate Zone Rating was +5.5 runs—an above average defensive mark (roughly half a win). At first glance of this rating, one might assume that Pence’s defense was strong in the outfield and that he did a combination of positive things, defensively, to earn such a score. However, it was Pence’s strong arm score of +5.9 runs that catapulted his UZR into the “above average” territory, while he was merely average with regards to range runs (-0.3) and error runs (-0.2). His UZR Chart makes this particularly clear as the ARM bar (green) and the UZR bar (red) are nearly identical. And so is the purpose of the UZR Chart, to detail what an UZR really means via an easy visual.

With that said – hopefully the explanation provided was clear (or clear enough, at least) – here’s another UZR Chart, though this one features a simple trend analysis of Derek Jeter’s Ultimate Zone Rating over the last five years.

As you can see from the chart, Jeter’s abysmal range (blue bars) from 2005 to 2007 essentially dictated his UZR. Outside of his ErrR in 2005, Jeter did not do anything particularly well in the field, either, as he was generally average in double play runs and error runs and terrible range-wise. His averageness did little to curb the damage brought onto his final rating by his range run totals. Whereas Hunter Pence has his great arm to increase his overall value, Jeter had nothing, really. Of course, in 2008, there is a noticeable change in Jeter’s defensive value, which is the direct result of a new training regimen employed by Jeter to address his range problems. His range improved tremendously – the blue bar ascends – and, thanks to a positive error runs total of 4.5, Jeter’s -0.5 UZR was his first average mark in years. The gains continued into 2009, as Jeter was worth 6.6 range runs. The area that was once a huge weakness is now a strength.

From now on, unless you guys see a mistake in this “method” that I am not seeing (comment away), when discussing and citing UZR totals from FanGraphs, I’ll probably offer an UZR Chart as well. It seems to be useful in pointing out the intricacies of the ratings so as to enhance understandings of a player’s defensive contributions (in a single year, or over time), as specific weaknesses – Derek Jeter’s range – or strengths – Hunter Pence’s arm – that may dilute or inflate an Ultimate Zone Rating are made apparent through such simple illustrations. By looking at a chart, it is much easier to decipher why an UZR score “is,” essentially. Plus, they’re fun to look at, too, which is an added bonus.

8 Responses to “Charting UZR can be useful…”

  1. Interesting article. Well written and explained.  (Quote)

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  2. Quick stylistic comment: I would change the UZR bar to something different in style (hash lines?) to make is clearer at a glance that it is meaningfully different than the other three bars. At first pass, I thought Hunter was above average at two aspects of UZR (though that’s obviously not true). Again, this isn’t a criticism so much as a style thing.  (Quote)

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    Chris H. Reply:

    Ah, good idea, Stephen. I’ll probably try to make the UZR bar clearer in the future (or at least stress, to a greater degree, that the UZR bar is different from the other bars).  (Quote)

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  3. Chris, with Jeter’s and now Tex’s uzr reports, I wasn’t going to touch it with the proverbial ten foot pole, but now that you explain it, I see a bit why it has produced such heinous results: it weights the three factors equally. That’s pretty ridiculous.  (Quote)

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    Moshe Mandel Reply:

    The weighting is really irrelevant, because the final result is a run value. Meaning, there is no weighting done, it is simply adding up how many runs each element was actually worth. It is a total, not an average, of the players defensive run value.  (Quote)

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    Chris H. Reply:

    I see what Smurfy is saying, but Mo is right on here. Run value is run value. I guess Ultimate Zone Rating, the name itself, might throw people off. Zone Rating, range, it all starts to conflate. Arm and error runs seem secondary because of that. Still, run value is run value.  (Quote)

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    smurfy Reply:

    If you guys say so, I guess, but I still got an eight foot pole. Mysterious to me where the run values come from, and those scores vs. the quality of ball handling apparent.  (Quote)

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  4. Good stuff, Chris. Really enjoyed it.  (Quote)

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