Cedric Mullins Goes Lefty Full-Time

Scan the WAR leaderboard, and you’ll find some expected names: Ronald Acuña Jr. atop the list with 1.5; Mike Trout comfortably in the top three; Vladimir Guerrero Jr. bashing his way into the top five. Yet nestled in at No. 9 with 0.8 WAR, wedged between a pair of Dodgers, is one of the bigger surprises of the season so far: Orioles centerfielder Cedric Mullins. Thursday’s pair of 0-fers in a doubleheader against the Mariners snapped an 11-game hitting streak to start the year, but his 19 hits are tied for third in the majors with Guerrero and Justin Turner (and one behind fellow sudden star Yermín Mercedes). Through 55 plate appearances, he’s slashing .388/.455/.571 with two steals, a .446 wOBA, and a 190 wRC+ — that last figure better than that of, among others, Aaron Judge, Corey Seager, and Nolan Arenado.

Mullins’ strong performance has been aided by a high BABIP (.500) that has to come down, but there’s more to it than that. His 10.9% walk rate is both a career high and three points above his career rate. His .184 ISO is over 100 points better than his last full-season mark (.063 in 2019). But most notably, Mullins, a switch-hitter throughout his career, is batting exclusively from the left side this season. So far, it’s paying off.

A breakout from Mullins this season wouldn’t be a complete surprise. A 13th-round draft pick in 2015 out of Campbell University, he rose through the minors on the strength of plus fielding ability and speed and occasional bursts of power. Going into the 2018 season, our Eric Longenhagen ranked him No. 6 in the Orioles’ system, writing, “He’s trending up, has tools and athleticism, and has performed, on paper, every year.” Mullins’ big league debut in 2018 was underwhelming and was followed by a smattering of cameos at the major league level since. But after slashing .260/.309/.440 this spring, he earned the starting centerfielder gig on Opening Day and secured a regular spot in the outfield after Austin Hays was sidelined by a strained hamstring.

While the offense hasn’t been there prior to this season, Mullins has been able to showcase his speed and defensive ability in the big leagues. He made 34 plays out of the zone in just 298.2 innings in 2020, good for eighth in the majors despite playing less than most of his counterparts, and Baseball Savant placed him in the 95th percentile in Outs Above Average that season with +5. He’s also been in the 90th percentile or above in sprint speed in all four seasons he’s played at the big league level. And he’s no slouch when it comes to power: He’s achieved average and maximum exit velocities at or slightly above league-average levels.

A few things stick out when you look more closely at Mullins’ production at the plate. He hits an enormous amount of infield fly balls, with a rate well over 20% in most seasons; last year’s 21.9% was fifth-highest among all hitters with 150 or more plate appearances. In 2021, though, he has yet to hit a single one. His O-Swing% has also greatly improved, going from 33.3% over the last two seasons to 22.8% this year. His hard-hit rate has jumped from 31.8% last year (and a 28.6% career mark) to 40.5%, which won’t top any leaderboards but, coupled with the better selectivity, suggests improvement in both making good contact and laying off pitches outside of the zone.

Some of Mullins’ early success is a product of the small sample; I’m certain he’ll hit his first pop-up of the season any day now. The commitment to switch-hitting is demanding, though, and by ditching his right-handed swing, he may be unlocking some hidden potential at the plate. During spring training, Mullins, who is a natural lefty, admitted that “it was getting difficult to try and create two different swings.” It doesn’t take much digging to see those struggles, particularly when he hit right-handed. From 2018 to ’20, he managed a grand total of 14 hits in 90 at-bats against southpaws, for a paltry .156 batting average. So far this season, he’s collected seven hits off them in only 15 at-bats, all from the left side.

It’s not often that a switch-hitter retreats back to hitting from their stronger side in all situations. The whole idea behind switch-hitting is that it gives the hitter a platoon advantage in every at-bat. To help understand, let’s take a look at the average platoon split in the majors over the 2019 and ’20 seasons.

As you can see, there is a significant benefit hitters get in batting opposite of the pitcher’s throwing arm, and the breakdown is similar for both left- and right-handed hitters, though it holds more weight for the former since nearly 75% of pitches are thrown by right-handers. Some batters, though, carry a negative split, so it’s not an exact science. Below is a histogram of the difference between left-handed hitters’ wOBA against right-handed and left-handed pitching over the 2019 and ’20 seasons (minimum 100 plate appearances versus both lefties and righties).

It’s not unusual for some very good left-handed hitters to have an extreme platoon split. Last year’s NL MVP, Freddie Freeman, has the largest platoon split by wOBA over the last two seasons.

Most switch hitters are natural right-handed hitters, and because the majority of at-bats they get are against righties, there is more of an incentive to try to master hitting from the left side of the plate as well. Mullins does not have that incentive. Going back through his days in the minors, he’s fought through many subpar performances facing lefties from the right side prior to giving it up this offseason. Looking at his splits during his time in the minor leagues, it’s been a long time coming.

Mullins performed similarly in the majors, with a .323 wOBA as a lefty but a .211 wOBA as a righty, producing a delta of .111; a typical wOBA split would be closer to .020.

It’s admirable to take on the challenge of two swings to get the platoon advantage, but it’s such a hard thing to do well. In the case of Mullins, he allowed data to inform a decision to go left full-time. I don’t think he’ll be looking back anytime soon.