Red Sox: Is Jackie Bradley Jr. actually an elite defender?

Red Sox center fielder Jackie Bradley Jr. has carried a reputation for being an elite defender all his career. Is that rep accurate?

Red Sox center fielder Jackie Bradley Jr. gets a lot of rope at the plate. And that’s understandable considering how much value he can bring with the glove. He’s been considered elite for as long as anyone has been paying attention to him, but has that always been true? Defense, like many baseball skills, is not consistent from year to year. That’s one of the reasons defensive metrics like UZR and DRS need three seasons to stabilize and become predictive. Thankfully, we have access to some of what StatCast can measure now, which may change the way we look at defense forever.

Now, StatCast data is new. As in, just a few full seasons have been subjected to it so far. That means that while we have some really interesting stuff to look at, we’re all still trying to wrap our heads around what the optimal way to use it is. Baseball Savant is the best place to go for metrics built upon this technology, and defensive data is no different. Unlike UZR or DRS, it’s a pretty good way to look at what’s happened so far in a partial season. So we can use it to see how he’s done thus far without worrying about the numbers being wildly misleading.

What does StatCast say?

Here’s a quick primer on the acronyms in these tables. OAA is outs above average. CPA is Catch Percentage Added. The 1-5 Star catches are the difficulty of catches made, with 5 being the hardest. Five star catches are made 0-25% of the time, as you can see denoted in the header. The percentages go up as the difficulty decreases. Since StatCast data goes back to 2016 for defense, we’ll grab the last two plus years of a few metrics and lay them out here. We’ll start with this table:

Year	OAA	CPA	5 Star 0-25%	4-Star 26-50%	3-Star 51-76%	2-Star 76-90%	1-Star 91-95%
2016	4	2	100.0%	70.0%	84.0%	90.9%	92.0%
2017	13	4	18.5%	71.4%	66.7%	100.0%	95.7%
2018	4	2	91.0%	50.0%	75.0%	92.3%	87.5%

The 2017 season stands out here as he had a much higher percentage of the really tough catches made. He actually ranked 12th in the majors among outfielders with at least 50 opportunities on balls in play for 5 star catches. If we look at just those with at least five 5 star catch opportunities, he moved up to 7th. What about the other categories?

How does that compare to the rest of the league?

Let’s lay this table out again with ranks by percentages. I’m using 50 opportunities overall and at least 10 opportunities per catch type on the 1-5 star catches in the full seasons. No minimums set for 2018:

Year	OAA	CPA	5 Star 0-25%	4-Star 26-50%	3-Star 51-76%	2-Star 76-90%	1-Star 91-95%
2016	T-11	T-57	T-24	6	25	T-42	57
2017	8	T-27	7	T-7*	T-47	T-1	40
2018	T-16	T-56	35	T-36	T-84	T-93	T-139

What I’m seeing here is not an elite defender, but rather, one who is capable of an elite season once in a while. That’s not to say he’s not a good defender. Quite the contrary. Jackie Bradley Jr. brings obvious positive value with his glove. But a truly exceptional defender should probably be ranking more highly in the difficult 5 and 4 star catches. As well as having a higher ranking in OAA or CPA.

That doesn’t jive with our perceptions. What gives?

If we take a look at Jackie Bradley Jr. as a center fielder by something that has been around longer, but takes more time to stabilize, it might shed some light on this. So we’ll take his UZR over the same span despite this season being a little less than half way done. It’s not quite a stable sample size, but the error bars aren’t too bad with just a half season of missing data.

With 8.2 UZR in 2016, then 3.7 last year, and 1.0 so far this season we have a total of 12.9 to work with. Divide that by three seasons and it’s 4.3 per campaign. That’s certainly an above average defender, but it’s not elite. So UZR seems to back up what we’re seeing in the table above. And no, we’re not short changing him by skipping 2015. He amassed 0.0 UZR in 224 innings that year. And just 1.2 in 262 innings in RF.

What’s the conclusion?

So I’m gonna come out and just say it: Jackie Bradley Jr. is overrated defensively. He’s not bad by any stretch, but he’s just not looking like an elite glove. Is he capable of making a spectacular play here and there? Absolutely. He’s made a few of the most eye popping grabs I’ve ever seen. But those plays appear to be the exceptions, not the rule. And big, emotional, important plays like that can stick in our memory and skew our perspective of a player. We grow to expect those kinds of plays and discount the missed plays as, perhaps, impossible or near enough.

This is why defense has been so hard to measure throughout the history of the game, by the way. It’s why some fans still think Trot Nixon was a better defender than J.D. Drew. Perspective is fluid and sometimes dangerous. In this case, it may be leading us to believe that Jackie Bradley Jr. isn’t just an above average defender. It’s making us think he’s great, or even elite. If he is, the numbers aren’t capturing that yet. And hey, in time, we may look back at UZR and the StatCast data the same way we look at Fielding Percentage now. Outdated as heck. But right here, right now? It’s tough to make the case for JBJ being an elite defender.

Next: Red Sox: Is Jackie Bradley Jr. still a major league-caliber hitter?

Have a data point you want to add? Care to take down the methodology? Want to just post a clip of one of his great catches? The comments are all yours!