A former 13th round draft pick, Mullins reached as high as No. 5 on MLB Pipeline’s top 30 prospect list for the Orioles back in 2017, but his career in the big leagues since being called up for the first time in 2018 had been unremarkable. He earned brief stints in the majors at the end of that season and the beginning of 2019, but he was sent down for the remainder of the latter after struggling out of the gates. He was back with the big club at the start of last year, this time staying up for the entirety of the shortened season and posting a respectable 0.6 fWAR in 48 games — a roughly 2-win pace across a full 162 — that mainly came on the back of his excellent speed and defense (he ranked in the 95th percentile in outs above average and 92nd percentile in sprint speed with seven stolen bases).
Given this context, it might come as a shock to see Mullins ranked all the way up at 8th on the fWAR leaderboard with a total of 1.7 six weeks into this season, tied with Vladimir Guerrero Jr. and right behind established sluggers like J.T. Realmuto and J.D. Martinez. His usual great defense has no doubt been part of this, but Mullins has also taken a huge step forward as a hitter so far this year, going from a slightly below average 97 wRC+ in 2020 all the way up to 149 so far this year. This sudden improvement at the plate has made Mullins one of the breakout stars of this season so far, and when you dig deeper into what has fueled it to this point, you’ll see that he might just be here to stay.
Stats as of 5/15/21
Left is Right
When looking into Mullins’s performance in the batters’ box in 2021, two different changes that he’s made stand out as the key reasons behind his success, with one being more noticeable and the other more subtle. We’ll start with the former, which is the fact that coming into the season, he decided to abandon switch-hitting and focus solely on hitting from the left side. Mullins fully committed to hitting just left-handed early into Spring Training this year, and according to the man himself, he did it because of the challenges that maintaining both swings at one time presented.
“It was getting difficult to try and create two different swings,” Mullins said. “I know my left-side is my natural side, so trying to develop my right-handed swing at the highest level was challenging. I tried to do the best I can to see if it could develop quicker. It just didn’t work out that way, so I felt going left on left was the best decision.”
On the surface, abandoning switch-hitting entirely feels like a pretty drastic step to take. It is common knowledge that same-handed pitchers are harder to handle for hitters than their opposite-handed counterparts, so never facing them at all seems like too significant of an advantage to just give up on the spot. Look at Mullins’ splits by handedness in 2020, however, and it becomes very easy to see why he made this decision:
As you can see, the difference between the two is pretty stark. From his more natural left side, Mullins was actually well above average at the plate, as a 118 wRC+ would have had him on the same level as Pete Alonso and Kyle Seager last year. He hit for a high average and got on base at a respectable clip while also not sacrificing power, with eight of his 10 extra-base hits coming while hitting lefty. From the right side, however, he couldn’t get much of anything going at all. He struck out more often as a righty, made hard contact at a less frequent rate, and saw his average and OPS both drop by significant margins, all of which make the decision he made before this season a lot easier to understand.
Dropping switch-hitting was pretty clearly the right thing for Mullins to do when looking at the numbers, but what wasn’t clear coming into 2021 was how he’d fare as a same-handed hitter against lefty pitchers, something he said he hadn’t done since his junior year of high school. Knowing this, it would be fair to assume that Mullins might require a bit of an adjustment period to refamiliarize himself with lefty-on-lefty looks, but so far this year, he’s held his own against them and then some:
Small sample size caveats definitely apply here given that this has come over the span of just 59 plate appearances, but Mullins has actually been one of the best lefty-on-lefty hitters in baseball through the first six weeks of the season. He has far surpassed his performance against southpaws last year while hitting right-handed, as, by wRC+, he’s gone from 66 percent below average against them to 69 percent above average. This giant step up in performance against lefties has been a huge development for Mullins considering where he was in previous years, and it came by making a change that many would consider unconventional.
Patience is a Virtue
As mentioned before, the other big change that Mullins has made this season isn’t as noticeable to the naked eye as abandoning switch-hitting is. It has arguably been even more important, though, as he has essentially reworked his whole approach at the plate with the goal of becoming a more patient hitter:
Mullins was never a prototypical free-swinger to begin with (his swing percentage in 2020 was only slightly above league average, and though he did chase a fair amount of pitches out of the strike zone, his whiff percentage ranked in the 73rd percentile of hitters), but he’s made a concerted effort to increase his level of plate discipline so far in 2021, and the early results coming from this have been pretty promising. His nearly eight percent decrease in chases has likely been a big factor in his strikeout rate dropping from a not great 24.2 percent to a lot more manageable 18.1 percent, and his walk rate has nearly doubled up to an above-average mark of around nine percent. A decrease in strikeouts and an increase in walks is usually a hallmark sign of an improving hitter, so the fact that Mullins has seen significant positive shifts in both is a pretty good indicator that his more patient approach in the box is working thus far.
Another thing that Mullins’s improved plate discipline has helped him with is getting into favorable positions in the box more often, as he’s seen an almost four percent increase in pitches seen while ahead in the count this year. This has forced pitchers to come into the zone against him more often than they had been before, and interestingly enough, his patience has persisted on these pitches as well:
Swinging at fewer pitches in the zone despite seeing more of them overall might seem like an example of Mullins being almost too patient, but what it has actually represented so far is Mullins being more selective with the pitches that he likes and waiting for ones to do damage on. Getting ahead in counts more has allowed Mullins to really hone in on his ideal pitches because taking strikes when he doesn’t get them isn’t hurting him as much as they would if he weren’t already in a good count. In addition, his seven percent increase in-zone contact rate illustrates that when he has gotten a pitch that he likes in the zone, he hasn’t been missing them as often as he was earlier in his career.
The numbers back up this line of thinking as well, as his overall performance on pitches in the zone compared to last year is a sight to behold:
This right here is what is at the heart of Mullins’s breakout performance. So far in 2021, he has been absolutely thriving on pitches thrown in the strike zone, and his improved plate discipline has been the catalyst behind it. He has been able to work himself into hitters’ counts way more often thanks to his newfound ability to avoid chasing pitches out of the strike zone, which in turn has allowed him to pick his spots with more frequency when pitchers do have to challenge him over the plate. He hasn’t been missing his pitches very often, either, and his sneaky-good power has finally shown itself in the big leagues because of it.
The 2021 season is obviously still very young, but what Mullins has done early on in the year inspires a lot of confidence that he can keep playing at a high level moving forward. His new approach at the plate and some of the shifts that have come with it paint a very good picture for his prospects of remaining an above-average hitter, and even if he does start to regress a little bit in the box (maintaining a .357 BABIP might be a bit challenging), he already has a pretty high floor thanks to his elite defense and blazing speed. You may not have known who Mullins was at the start of this season, but you better start paying attention to him now, as he is firmly putting his name on the national map.
Photo from Randy Litzinger/Icon Sportswire | Design by Quincey Dong (@threerundong on Twitter)