Baseball Fam has a roaring debate going on right now: who’s the best defensive shortstop in baseball? There are a number of ways to determine the “best” at any given category. Historically, the “eye” test and basic statistics such as errors and fielding percentage have been the baseline for observations. In recent years, advanced statistics have given us a much clearer picture in to the defensive side of the game. Simply put, advanced statistics give us a much better idea of a player’s true value to his team defensively than the “eye” test or fielding percentage ever has. Per usual, all statistics in this article are credited to Fangraphs.
Why Errors and Fielding Percentage fail to do the job
Historically, fielding has been measured in errors. The less errors a player has, the more quality defender he was thought to be. Unfortunately, this statistic does not accurately reflect a player’s true contribution to his team. Errors only record plays that a fielder fails to make, but does not reflect easy balls that a player fails to get to because of a poor jump or miscommunication. If we’re looking for the best defensive shortstop in baseball, shouldn’t we look at the bigger picture? Instead of attributing runs saved or given up to certain fielders, the error statistic only tracks the amount of routine plays they did not make in a given period. Just as we attribute runs to pitchers using the Earned Run Average statistic, why shouldn’t we attribute runs to fielders? Ultimate Zone Rating seeks to do just that.
What is UZR?
UZR is a defensive statistic measured relative to average at a certain position. For example, a shortstop with a UZR of +5 is statistically five runs better than the average Major League shortstop. UZR is calculated by adding or subtracting runs to a player’s UZR depending on how hard the play is and how often a play like it is made. For example, if the average shortstop makes a certain play 50% of the time and a ball is hit to him that is worth .5 runs (based on speed, location, ect), by making the play the shortstop earns .25 (50% * .5) to his UZR. The calculation of UZR is enough to make your head spin, and the folks over at Fangraphs do a great job of explaining it in detail if you want to know the ins-and-outs of UZR. For our purposes, using a statistic of UZR is significantly better than the “eye” test because we are not physically capable of remembering every play a player makes in a particular year and accurately giving a player a true defensive rating. UZR attributes runs to certain defenders, and this does give us an accurate representation of a player’s defense. Players with higher UZR scores are better defensively because they save more runs and give up less runs than the average defender. The same could be said for low UZRs and being worse defensively. UZR over a period of time (in our case just over one year) gives us a way to accurately compare certain players of the same position against each other
Comparing players using UZR
Because sample size is so important in statistics, we will use UZR ranging from the beginning of the 2015 season until May 14, 2016. Below are the Top 5 and Bottom 5 UZR ratings from 2015-today for the 27 qualifying shortstops.
- Andrelton Simmons 22.0 UZR (22 runs better than the average shortstop)
- Adeiny Hechavarria 19.4 UZR
- Brandon Crawford 17.4 UZR
- Nick Ahmed 15.4 UZR
- Francisco Lindor 12.3 UZR
- Jhonny Peralta -7.2 UZR (7.2 runs worse than the average shortstop)
- Asdrubal Cabrera -8.3 UZR
- Marcus Semien -9.9 UZR
- Erick Aybar -10.9 UZR
- Carlos Correa -12.8 UZR
While I could make some observations based on UZR, some of you will undoubtedly argue UZR is an unreliable statistic. While the sabermetric genius’ of baseball would vehemently disagree, I will also include Top and Bottom 5 Defensive Runs Saved (another advanced statistic) to make my point. Full disclosure: Jose Reyes has been removed from the list at 24 because of his current situation with the Rockies.
- Andrelton Simmons 32 DRS (32 runs better than the average shortstop)
- Nick Ahmed 27 DRS
- Brandon Crawford 26 DRS
- Francisco Lindor 12 DRS
- Adeiny Hechavarria 9 DRS
- Carlos Correa -6 DRS (6 runs worse than the average shortstop)
- Johnny Peralta -7 DRS
- Erick Aybar -9 DRS
- Asdrubal Cabrera -10 DRS
- Jimmy Rollins -11 DRS
It is important to remember that no metric will ever give you a 100% accurate quantification of a player. What metrics are able to do is attribute runs to players based on their defensive ability using a large number of variables that our brains are not able to track all at once. Based on these metrics, to suggest (as has been done before on Baseball Fam) Carlos Correa and Francisco Lindor are on the same level defensively is certifiably insane.
Follow me throughout the season on twitter @texanthony115 and on Baseball Fam to see more baseball myths debunked By The Numbers.