Rafael Devers already looks like a better player in 2018

Rafael Devers‘ early, improved plate discipline makes it seem like he is a better player

Featured image courtesy of Zimbio.com: (March 29, 2018 – Source: Brian Blanco/Getty Images North America)

With Xander Bogaerts, Mookie Betts and Hanley Ramirez all off to torrid starts, it can be easy to overlook Rafael Devers. After all, the young third baseman batted 8th, behind Mitch Moreland and Eduardo Nunez, in yesterday’s contest with the Tampa Bay Rays. It can, admittedly, be hard to garner recognition that low in the order.

Devers, just 21-years-old, burst onto the scene with the Boston Red Sox late in the 2017 season. He clubbed eight long balls in just his first 20 career games, including one of the most impressive and improbable home runs in baseball history. At times, he seemed to be the answer to the Sox’ year-long offensive drought. A budding superstar, even.

Then, the league adjusted to the recently-legal kid on the hot corner, as he struggle to replicate the magic of his first 20 games. His defense was spotty and his free-swinging ways were exploited. He ended the year with a respectable, albeit seemingly relatively disappointing, 111 wRC+. 

Given the enormous potential and flashes of offensive brilliance, Devers is a captivating player to watch. How would he respond to the adjustments made against him late in the season? Baseball, at its core, is a constant battle of adjustments.

Anyway, while it is just eight games worth of data (36 plate apperances), the early results seem encouraging for the Dominican Republic native. He has posted a sterling 163 wRC+, posting a .417 OBP and .548 SLG to begin 2018. This, along with better defense (2 DRS and 1.3 UZR), has led him to produce a 0.5 fWAR already in the new season. For context, Devers was worth just 0.8 fWAR in 240 plate appearance in his ’17  campaign.

Yes, Devers’ results on both side of the ball seem to instill hope in the hearts of Red Sox fans, but we must apply a small sample size caveat and take a look at some underlying numbers. Raffy Big Stick (thanks Baseball Reference for the nickname!) has accompanied his stellar offense performance with an unsustainable .375 BABIP (batting average on balls in play).

Generally speaking, a BABIP that high usually signifies that “lucky” batted ball placement has influenced his production. To put it bluntly, there is a good chance he experiences some offensive regression as the year progresses. Granted, he does have a little bit of wiggle room coming from a 163 wRC+.

Truthfully, though, I am not really concerned with these volatile and far from stabilized statistics. They are worth noting but with a hefty grain of salt (I love oxymorons).  There are a few things Devers has done early, however, that do seem predictive and signs of an improved player.

Devers has improved his K% and BB% numbers considerably in the young season. Sure, it is early but both of those are numbers that stabilize demonstrably quicker than other stats. In other words, they have more staying power and are not as random variation driven at this point. Check out this excerpt from Fangraphs on the subject:

With respect to sample size, it’s important to know that K% and BB% tend to “stabilize” in a relatively low number of PA. You don’t need more than about 60 PA for K% or 120 PA for BB% before the numbers start to become meaningful, which means that it’s very unlikely that even a half season of K% or BB% are simply functions of random variation. More directly, a player’s K% and BB% are skills that you can estimate from a reasonably small amount of data. This means that if you have a good sample of PA, you can feel good about the validity of the information you’re using.


To reiterate, Devers has accumulated 36 plate appearances, so we are not quite there yet but we are kind of close. And I will be damned if I do not overreact to being “kind of close.” For your viewing pleasure, I have devised a table for you to see the improvement in these categories (and others!). Enjoy the return of the table.

 Season PA K% BB% O-Swing% Z-Swing%
2017 240 23.8% 7.5% 38.5% 64.5%
2018 36 16.7% 13.9% 37.4% 76.6%

Look at those improved numbers! The free-swinging left-handed hitter has cut his strikeout percentage down and shot his walk percentage up. Both of those are good things. Meanwhile, he has swung at less balls (O-Swing%) and, like most Red Sox hitters, has swung at a lot more strikes (Z-Swing%). I do not know how your eyeballs walk away from that table not brimming with excitement.

These are numbers worth getting giddy about because they matter more than most other stats at this early juncture. Plus, they are not small differences. He is walking six percent more and striking out seven percent less. Both of those numbers are trending in the right direction. Moreover, his offensive results have not suffered a lick from the alteration of his plate discipline.

Rafael Devers has a boatload of potential. You know that and so do I. Expectations are high for him and rightfully so. Anecdotally-speaking, he has some of the best raw power I have ever seen from a player.  The power is tantalizing but if he were able to maintain his plate discipline numbers, or something close to it, and combine it with his hitting ability, he may transcend the player we thought he could be.

The Boston Red Sox are looking really good in 2018, with numerous players putting on clinics to begin the year. It may take Devers two or three innings to get his first plate appearance of the game but, make no mistake about it, he is putting on a show for Boston.

Patrick Green

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

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