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What the new Statcast infield defensive metric has to say about the Red Sox

They like them more than some other metrics.

Baltimore Orioles v Boston Red Sox Photo by Maddie Meyer/Getty Images

On the list of issues for this Red Sox team heading into 2020, the infield defense probably isn’t too high for most people. After what the pitching staff did last season, that is the focus, and for good reason. That said, depending on who you ask and/or what metrics you look at, the infield glovework is average-at-best, and potentially much, much worse than that. Based on what I saw last year — and I didn’t really watch José Peraza, so that’s a pretty big unknown — I would probably have them a little worse than average. But there is obviously plenty of room for disagreement.

Now, we have a new tool to add to our evaluations, as Statcast has unveiled their Outs Above Average (which will sometimes be referred to as “OAA” moving forward) metric for infielders. It has been around for outfielders for a couple of years now. You can read the short(er) explanation here or, if you prefer, the long and in-depth one here. The bullet points here, which are from that first link, are as follows:

• How far the fielder has to go to reach the ball (“the intercept point”)

• How much time he has to get there

• How far he then is from the base the runner is heading to

• On force plays, how fast the batter is, on average

So, the big difference here from DRS (as it stands now. There is an update coming soon) and UZR is how much it takes shifts into account. By this new OAA metric, the Red Sox infield overall ranked slightly positive and ranked 16th in the league. The infield personnel will not be exactly the same in 2019, of course, but this is a good barometer for where they stand by this metric.

Boston Red Sox vs New York Yankees Photo by Paul Bereswill/Getty Images

Before I get into the individual players, I should mention that I am — and many people are — a little skeptical of defensive statistics in general. There is a lot of noise in every metric we’ve seen to this point, and it is easily the hardest part of the game to measure. That is not to say they should be totally ignored, but rather no one metric should be relied on by itself. This OAA metric is no different, which I think their creators would agree with as well. It is instead another tool being added to the chest with which we can try to more accurately evaluate a player, not perfectly evaluate one. More tools are always better than fewer.

Anyway, with all of that out of the way, let’s take a look at the individual players who are currently projected to make up the Red Sox infield. Obviously nothing is set in stone here yet, but for the purposes of this post I’m assuming José Peraza is the starting second baseman and Michael Chavis is the starting first baseman.

Rafael Devers

2019 Player Page

We’ll start with Devers, because to me he is pretty clearly the most interesting defensive player on the roster. His glove was a major question coming up, and the early returns didn’t help the poor reputation. Hell, just a month into last season there were questions about when — not if — he would move off the hot corner. Then, he turned it around in a big way, and many of us saw him as an average-to-plus third baseman.

OAA agrees. From 2018 to 2019, Devers was one of the most improved infielders in the game, going from costing the Red Sox seven outs with his glove to adding seven. The biggest difference was when he was playing back. As you’ll see in the graphic below — where the red boxes are positive OAA and the blue are negative while the size represents how often he was positioned in each spot — Devers was at least solid in both seasons when playing in. When playing back behind the bag, he made massive strides.


In addition, and perhaps related, to the improvement was Devers’ ability to move to his left into the hole towards shortstop. He was positive when moving laterally towards first base in 2018 as well, but he took a leap towards elite in 2019. In fact, his nine outs above average here ranked second among all third basemen in baseball, trailing only Nolan Arenado. If you are trailing only Nolan Arenado in anything related to third base defense, you’re doing okay.

I’ll also mention that OAA has monthly splits as well, which to be fair I’m even more skeptical of. A full year often isn’t enough for a defensive metric to stabilize, so a month is a really small sample. That said, his month-by-month OAAs were as follows, starting in April: 0, 3, 3, 1, 0, 0. That does follow what I would have thought from my own eye test, for whatever that may be worth.

Xander Bogaerts

2019 Player Page

Bogaerts is another interesting case because the two main defensive metrics before OAA was released — DRS and UZR — differed wildly on the shortstop. While UZR saw him as a slight positive, DRS viewed him as perhaps the worst defensive player in the game. I’ve always kind of thought the answer was a little in between — he’s below-average in my eyes, but not to any sort of crippling degree. His 2019 defensive numbers agree with me as he finished with a -3 rating. That said, he was a +2 the year before, so if you take them together he’s about average.

If you’re looking for the big differences between the seasons, they came when Bogaerts was playing back almost on the grass and when he was coming in. Obviously, a lot of times those two instances are often the same. For the former, you can see the graphics below. Again, notice the contrast between blue and red squares.


On plays coming in, he went from on OAA of +7 in 2018 to an even 0 in 2019, a staggering drop. I’m a little surprised because I felt like he was still very good at this in 2019, but that could surely be some confirmation bias on my part after he was one of the best in the league in this area earlier in his career. It is worth mentioning that Bogaerts went from being ranked second when coming in on the ball in 2018 to 22nd in 2019. It is also worth noting that he improved a bit on plays moving to his right (-5 to -2), but that’s always been a weak spot for him.

Michael Chavis

2019 Player Page

Chavis is the infielder who most proved me wrong last year. Devers certainly surprised me with just how quickly he improved, but I always saw the tools for a solid third baseman. I thought the Chavis experiment at second base would be a disaster. Instead, at least by the eye test, he was more than solid there. It wasn’t Gold Glove defense, but it worked.

OAA saw it similarly at both second base and first base, the latter of which is where he is more likely to see the bulk of his playing time at this point. Overall, he was rated with +4 OAA with two outs being added from each position. He had 100 plays as a second baseman and 69 as a first baseman. Obviously, there is no 2018 to compare here, but at both positions he was better moving side-to-side than he was moving forward and back.

What’s most interesting about Chavis was the type of plays he was making at first base. In terms of the rate at which he actually made the play, Chavis was 30th (out of 40) among all first baseman with a success rate of 90 percent. However, he still rated positively because his expected success rate was second lowest in baseball, ahead of only Edwin Encarnación. I’m not sure if that’s just bad shifts — the Red Sox infield as a whole was 23rd in expected success rate — bad individual positioning, small sample size noise or something else entirely, but it’s definitely something I’ll be eyeing in 2020.

José Peraza

We end with the guy we are most unfamiliar with. Peraza has spent time at both middle infield spots, spending most of last season at second base but most of 2018 at shortstop. In 2019, he was slightly positive at second base with +1 OAA. That is compared to a +5 at shortstop. He was also similar to Chavis in that he had one of the lowest expected out rates at the position last season. His biggest strength, at least by this metric, seems to be moving to his right towards the middle. I really don’t have much to say here, to be honest, because I don’t really have the knowledge of watching him to compare with. I will say that, as a team, the Red Sox were +3 at second base last season.