Spring training is the time we hear the most about defence. Loud discussions of “getting back to basics” and “focussing on fundamentals.” Basically, all crap. But defence remains invaluable, a huge part of run prevention; itself a huge part of winning.

As fans we have access to an increasingly large number of advanced defensive statistics. Some use video technology to evaluate each batted ball against a league-wide databazzzzzzz sorry, I know it can get a little dry. The point is this: fielding percentage is dead. But there are so many current pretenders to the throne it can be hard to decide which is fit to wear the crown.

It is tough to advocate any one system over the other, in fact I like to use them all in concert. If a guy rates well in multiple systems, it is safe to say he’s decent with the leather. What really interests me when the systems disagree. Join me after the jump where I compare some of the most prominent defensive stats.

The most prominent current defensive metric is ultimate zone rating or UZR. Used in Fangraphs’ WAR calculation, UZR is a video-based system which has come under fire of late. While not perfect, it works best when you look at a large (3-year?) sample. Pack a lunch and read the full explanation at Fangraphs.

Defensive Runs Saved is also known as plus/minus and currently falls under the Bill James Umbrella of Nerditry. DRS uses video much like UZR but parses the data in a different way, as we will see below. Read a full FAQ at the Fielding Bible homepage for more insight.

Total zone is the creation of noted Sabr-dude Sean Smith. The system doesn’t use video data but play-by-play and batted ball types to divvy up responsibility among fielders. Read the full explanation at Baseball Reference, which uses TZ as the defensive component for their version of Wins Above Replacement.

Below is a three year (2008-2010) sample of qualified outfielders, comparing UZR to TZ. Why outfielders? In my mind there shouldn’t be a much grey area for batted balls once they reach the outfield. I’m trying to give the systems the benefit of the doubt, really I am.

The biggest thing to look for is disagreement between the samples. The upper left quadrant shows players who UZR doesn’t like but TZ loves while the bottom left is the reverse. This disparity fuels large differences between rWAR and fWAR, which undermines the entire process. Any names jump out? Click the image for a larger, clearer version.

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Michael Bourn and Hunter Pence! This, to me, is more than mildly shocking. Defence has long been a calling card of the speedy Bourn, while Pence is very well known for his incredible throwing arm. That these two bros are teammates makes me wonder if Minute Maid Park doesn’t play a huge factor. One huge failing of play-by-play data is the perception of stringer bias; wherein one man’s line drives are another man’s bloopers. Let’s look below at the DRS and UZR comparisons to see if anyone else jumps off the screen.

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J.D. Drew! Everything I’ve been told is a lie! Drew ranks as excellent by UZR but sits just below average when viewed by Bill James. Jeff Francoeur is always the lightning rod, here feeling some love from the DRS people while UZR isn’t quite as bullish.

Looking at the two graphs at the same time, a few names jump out as guys UZR hates but the other two players love. Torii Hunter has nearly identical DRS and TZ numbers (in the positive) but feels UZR’s scorn. Ryan Ludwick and Colby Rasmus both get a boost when you look at video versus the detailed box score.

In the end, there is a lot of agreement. Death to Flying Things, Ichiro, and Carl Crawford are good at their jobs while Brad Hawpe may or may not be paralyzed. Vernon Wells and Delmon Young make all the systems weep just like Jayson Werth and Justin Upton make them swoon.

One last bit of info: a list of the top 10 guys who confound the systems the most. The total amount of disagreement between the three systems. It is worth noting the systems all agree Jermaine Dye is awful, they simply express their hate in varying degrees.

  1. Hunter Pence.
  2. Michael Bourn
  3. Jeff Francoeur
  4. Alfonso Soriano
  5. Torii Hunter
  6. Shin-Soo Choo
  7. Jermaine Dye
  8. Ryan Ludwick
  9. Curtis Granderson
  10. B.J. Upton