If you’ve watched Ronald Acuña Jr. hitting for the first month and a half of the 2021 MLB season, then you probably know he has been hitting out of his mind. As of May 16th, out of 163 qualified hitters, Ronald Acuña Jr. is third in OPS, seventh in wRC+, and fourth in fWAR. While being in the top 10 of all these stats is incredibly notable, I personally thought Acuña would at least be top five in wRC+. If you’ve watched his plate appearances this year, you would know he pretty much crushes the ball in every plate appearance, so what gives?
Looking at his batted ball profile via Baseball Savant, it was safe to say that something was up. Ronald Acuña Jr. ranks first in xwOBA, second in xSLG (by .001), and fourth in xBA among 305 qualified hitters by balls in play. So we almost doubled our number of hitters to compare Acuña to, and his expected stats outperformed the few hitters who are currently outperforming his actual stats. So if Ronald Acuña Jr. is first in xwOBA, why is he 19th in OBP? If Byron Buxton has an xSLG of .696 and Acuña Jr. has a .695, why is Buxton actual slugging % .772 while Acuña Jr.’s is only .646?
The simple answer: bad luck.
Ronald Acuña Jr. Hitting: Rotten Luck
Ronald Acuña Jr. has had his fair share of injury scares so far in 2021, such as an abdominal strain on April 18th, being hit in the hand by a pitch on May 9th, and injuring his ankle while running to first on May 13th and subsequently having to leave the game. But this isn’t the bad luck I’m talking about. Objectively, with so many injuries across the league and to Braves’ outfielders in general, the fact Acuña hasn’t seen any time on the IL is pretty good luck. The bad luck I’m speaking of that has plagued Ronald Acuña Jr. so far this year has been from the proverbial baseball gods giving him bad luck on balls in play.
Here we are able to see a correlation between BABIP and wRC+, which makes sense. The more balls in play that are base hits the higher your wRC+ is. While not striking out is undoubtedly good, putting balls in play that are easy outs renders the same outcome as a strikeout most of the time.
All outs were not created equal, but the majority of outs don’t have any positive outcome to go along with it such as a sac fly to score a run or a ground ball that moves a runner up 90 feet. So how is Acuña Jr. keeping his wRC+ in the top ten of hitters with a BABIP that is 105th out of 163 qualified hitters? And does this mean he’s due for regression or will his actual stats trend towards his expected stats?
First off, in 2021 Ronald Acuña Jr. has effectively cut his strikeout rate in half. From 2018-2020 Acuña Jr. averaged a strikeout rate of 27.1% with a career-high in 2020 of 29.7%. In 2021 his strikeout rate currently stands at 15.6%. That kind of improvement is nothing short of astonishing, and with fewer strikeouts this year he’s obviously putting more balls in play.
In the shortened season of 2020, Ronald Acuña Jr. has 202 plate appearances and exactly 100 batted balls in play. In 2021, he has only had 154 plate appearances so far but already 108 batted balls in play. So, with more balls in play, the low BABIP must be an issue of quality of contact, right? More balls in play but a BABIP .020 percentage points lower than 2020 must mean that the majority of balls he is putting in play are easy outs.
Well, if you remember earlier we said Ronald Acuña Jr. is first overall in xwOBA, so his quality of contact is obviously not the problem. Could it truly be just an issue of bad luck? To find an answer to that, let’s take a look at how other players with similar BABIPs perform.
For starters, we know Acuña Jr. has a BABIP of .281 so how do qualified hitters around there perform? 61 qualified hitters have a BABIP from.250-.300 with an average wRC+ of 100.95. However, there was no real correlation between wRC+ and BABIP in this sample:
Essentially, quality of contact is still the prime factor when looking for a correlation between balls in play and success. But when we look at wRC+ for qualified hitters with a BABIP of .300, there is a more prominent correlation:
Of 79 qualified hitters with a BABIP of .300, the average wRC+ rises all the way to 129.48. Unsurprisingly, the more base hits a player gets on average, the better his performance and therefore he will have a higher wRC+. So where does Acuña Jr. fit into this? The best way to state it is that Ronald Acuña Jr. is hitting the snot out of the ball right at people, essentially meaning he’s just getting really unlucky, and he’s still hitting just as well as the best hitters in the league.
20 qualified hitters have a wRC+ greater than 150. Of those 20 hitters, the average BABIP is .365, five players have a BABIP over .400, and only one player has a BABIP less than .300, you guessed it: Ronald Acuña Jr.
If you take one thing away from this article, let it be this: Ronald Acuña Jr. is just getting started. If he can stay healthy and stay on the diamond, he’s on an MVP trajectory. If his batted ball profile remains to be elite, and there is no reason to think it won’t be, he’s going to get an uptick on average for balls in play because in baseball everything typically evens out over the marathon 162. If his BABIP reaches the threshold of .300 or .350 and his strikeout rate remains below 20%, Acuña Jr. is going to run away with the 2021 NL MVP award.
From 2015-2020, only two qualified hitters have finished with a BABIP greater than .400; Yoan Moncada with .406 in 2019 and Michael Conforto with .412 in 2020. It’s probably safe to assume that Mike Trout’s outrageous BABIP of .456 so far in 2021 won’t be that high come October, likewise, we can safely assume Ronald Acuña Jr.’s BABIP won’t be below .300 come October either. So watch out MLB, watch out baseball gods, watch out world, because you can try to keep Ronald Acuña Jr. down, but he’s never out. And so far in 2021, the young superstar has beaten bad luck.
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