Defensive metrics seem torn on Jackie Bradley Jr.

Featured image courtesy of (Aug. 30, 2018 – Source: Dylan Buell/Getty Images North America)

Even when Jackie Bradley Jr.‘s bat is ice cold, there’s more than a compelling argument to keep him in the lineup. You see, JBJ is an absolute defensive stud, making highlight reel catch after highlight reel catch. People generally underrate defensive value and performance when evaluating individual players, yet even they seem to understand the immense value that derives from the Red Sox center fielder’s glove.

Perhaps bordering criminality, he has never been awarded a Gold Glove. You know who has, though? Mookie Betts, his companion to his left, manning right field on a daily basis. Betts has won two consecutive Gold Gloves and, like Bradley Jr., is regarded as one of the best fielders in the game. Despite this fact, Red Sox fans still seem pretty adamant on which Boston outfielder is the supreme defender.

Now, referencing the previous paragraph, one should not use trivial accolades to factor into the discussion of which player is the defensive superior. I tried to answer the question more objectively on the Daily Dose of Red Sox, conveniently located on the menu at the top of your page. Here’s what I wrote on August 23rd:


“Though defensive metrics are generally thought of as a bit unreliable, each outfielder has a large enough sample to where we can extract useful information. According to the metrics, Betts (94 career DRS, 52.1 UZR) is decidedly the better defender over Bradley Jr. (45 DRS, 34.4 UZR). They have both logged roughly the same amount of innings in the field, so these cumulative stats become meaningful. In fact, JBJ has actually played 200 more innings in the outfield than Betts in his career.

Even though, again, defensive metrics are not the end all, be all but, with a gap that significant, one has to understand there’s substance to it. JBJ is admittedly more flashy, with Betts appearing more nonchalant on many tough plays. Still, the Red Sox right fielder seems to be the definitively better defender than the Red Sox center fielder.”

I vehemently stand by my assertion of Betts’ defensive dominance. The gap between them is simply too hard to ignore, especially with two different all-encapsulating (at least in theory) defensive metrics. Regardless, this led me to examine JBJ’s defensive metrics like a hawk and something rather peculiar emerges in 2018.

Over on Fangraphs, his defensive value seems to be in peak form with an 11.4 defensive score, factoring in fielding and positional adjustment. As of now, that is his second-best mark in his career, only being beat out by his 2014 season of 13.0. Obviously, there is still twenty-something games left in the season, so there’s time to match or surpass that score. A quick glance at that would be surprising to no one. A deeper dive, however, may leave some observers dumbfounded.

So, as mentioned, there are two all-encompassing defensive metrics used to essentially evaluate how many “runs” a defender is worth. They are UZR (ultimate zone rating) and DRS (defensive runs saved). Here’s a primer on the similarities and differences of the two, via the Fielding Bible.

“Both systems have the same goal- estimate a player’s defensive worth in units of “runs”, and both rely on hit location and type data from Baseball Info Solutions. The differences lie in the various adjustments and calculations that are made.

For example, Defensive Runs Saved uses a rolling one-year basis for the Plus/Minus system, while UZR uses several years of data to determine each play’s difficulty level. Defensive Runs Saved also includes components to measure pitcher and catcher defense.”

The two stats correlate pretty well with each other but can be torn on certain players. Well, this season DRS and UZR are clashing on Bradley Jr.’s defensive value. In terms of UZR, Bradley Jr. has been one of the premier defenders in the sport, sporting an outstanding 8.9 UZR in center field that places 6th in all of baseball in 2018. This metric rates him highly on range and arm, especially the latter where he has provided tremendous value with his cannon (per usual).

In contrast, JBJ has an exactly 0 DRS in center field this season, which is the epitome of average. Among qualified players, this ranks 72nd out of 133 fielders. His DRS is tied with Mitch Moreland, who, no offense, is not in the same breath as the former University of South Carolina star in terms of defensive acumen. If we expand his DRS to every outfield position he’s played this season, his DRS rises to 2, which still makes him a slightly above-average defender.

I’m not sure anybody would classify Bradley Jr. as an “average to slightly above-average defender.” It is not like this is a consistent debate between the two heralded statistics, as he usually rates well with both. In fact, he has scored a DRS between 8-15 in each of his last four years. This season is, by all indications, an anomaly for DRS and Bradley Jr., which is pretty volatile stat to begin with. Generally speaking, it takes 1-3 years for these metrics to become meaningful. We are essentially at the lower end of that stabilization point but the data may just be the result of too small of a sample.

Where has he suffered in DRS components? It seems like his rGFP (Good Fielding Plays) and rPM (Plus/Minus runs saved) have each taken a hit this season. In center, he had a 7 rGFP in 2017 and a -1 rGFP in 2018. That explains most of it, though his rPM has also dropped slightly.

StatCast rolled out another interesting defensive metric fairly recently called Outs Above Average. Here’s their succinct definition on OAA.

“Outs Above Average (OAA) is the cumulative effect of all individual Catch Probability plays a fielder has been credited or debited with, making it a range-based metric of fielding skill that accounts for the number of plays made and the difficulty of them. For example, a fielder who catches a 25% Catch Probability play gets +.75; one who fails to make the play gets -.25.”

In OAA, Jackie Bradley Jr. reigns as one of the best defenders in range, which is, you know, an incredibly important part of defense. He ranks 8th in the stat with a robust 10 OAA score and an expected catch percentage of 86% and an actual catch percentage of 89%. In other words, he’s added three percent.

Adding my own fallible eye test into the equation, I’ll happily conclude that Jackie Bradley Jr. is one of the best defenders in the game. It is interesting to see the disagreement between the two popular defensive metrics on his defensive value, which have never really contended in the past. This should not temper one’s perception on JBJ’s defensive abilities, rather, it exists as an attempt of as an objective evaluation on his defensive value as possible.

Still, it seems one of the game’s best defenders will have a real shot at winning his first Gold Glove of his career this season. If so, he would damn deserve it.


Patrick Green

Founder and owner of Red Sox Unfiltered. Communications major at UNCC.

You may also like...

1 Response

  1. November 5, 2018

    […] in September, I detailed the twofold view the defensive metrics have about JBJ’s defense. Basically, UZR supported the indisputable notion that Bradley Jr. was the best center fielder in […]

Give us your thoughts on this topic...

This site uses Akismet to reduce spam. Learn how your comment data is processed.