Marlins J.T. Realmuto living a double life

The catcher position is not particularly deep in the National League this season, giving J.T. Realmuto (.310/.350/.425, 104 wRC+, 0.7 fWAR in 120 PA) a legitimate shot to earn his first All-Star selection in July. I’m genuinely curious to see what kind of reaction he would receive during player introductions at Marlins Park.

While Realmuto has performed at a #nice level throughout his home career, he’s been dramatically better at other venues, particularly in 2017:

• .237/.260/.372, 9 HR, 69 wRC+ in 551 PA during home career; .327/.366/.467, 14 HR, 124 wRC+ in 611 PA during road career
• .163/.200/.186, 0 HR, -2 wRC+ in 45 PA at home this season; .400/.440/.571, 2 HR, 166 wRC+ in 75 PA on the road this season

Realmuto’s bat does a pretty convincing Yogi Berra/Joe Mauer impersonation on the road (both career 124 wRC+). In Miami, though, he’s more like lifetime backup Chris Stewart (career 69 wRC+). Since seizing primary catching duties, the 26-year-old has racked up enough playing time—1,162 plate appearances entering Friday’s game—to surpass nearly all of the “stabilization points” for offensive stats. In other words, it might be time to begin taking these quirky splits more seriously.

FiveThirtyEight’s Neil Paine recently used Sports-Reference data to conclude that home-field advantage means less in baseball than it does in the other North American team sports. Even so, throughout 25 seasons of Marlins franchise history, MLB teams have consistently been at their best when sleeping in their own beds. League-wide On-base Plus Slugging percentage has been higher at home every year, including a 26-point differential last summer (.752 OPS vs. .726 OPS) and a 37-point differential so far in 2017 (.749 OPS vs. .712 OPS), per Baseball-Reference.

Marlins Park is notoriously pitcher-friendly, but many of Realmuto’s teammates show a preference for hitting there, anyway. For example, Justin Bour (.273/.351/.500 at home, .248/.317/.420 on road) and Dee Gordon (.328/.368/.403 at home, .285/.309/.364 on road) have posted conventional splits in their careers with the Fish.

It’s not simply that Realmuto is an exception to the norm—there isn’t any precedent for a Marlins player underachieving at home to such an extreme degree. Among all players to log at least 600 plate appearances for the club (approximately a full-season’s worth), only Donovan Solano even came close to exhibiting this tendency.

The reality of Marlins Park is that its dimensions and playing conditions suppress home run totals. We can’t all be Giancarlo Stanton, clearing the outfield fence by 10-15 rows whenever barreling up a pitch. According to ESPN’s Park Factors, the stadium has ranked in the bottom five across Major League Baseball in home run rate in every full season since opening. That means plenty of would-be long balls result in doubles or fly outs instead.

However, the opponent ballparks that the Marlins visit most frequently don’t make it particularly easy to hit one out, either. Citizens Bank Park is the only NL East venue that consistently finished top 10 in home run rate.

Besides, that’s just a minor part of Realmuto’s batted ball profile. Dating back to 2014 (his first MLB season), he ranks in the bottom third among MLB players with a 32.0 fly ball percentage (min. 1,000 PA), per FanGraphs.

Photo by Jason O. Watson/Getty Images

So, is J.T. inconsistent with his plate discipline? Not really! His walk rate barely budges , 4.4 percent at home compared to 4.7 percent on the road. Meanwhile, his strikeout rate actually improves at home (15.9 percent), as he gets K’ed 17.7 percent of the time elsewhere.

Solving the mystery of Realmuto’s splits requires an investigation of his balls in play. He boasts an incredible—and in all likelihood, unsustainable—.383 BABIP on the road. At Marlins Park, that figure takes a plunge to .268. For context, MLB’s overall BABIP has hovered around .300 in recent seasons.

Perhaps luck is a big influence here, but Baseball Info Solutions also detects a tangible change in the quality of his contact. Realmuto has a career 21.8 Soft% at home, but only a 18.8 Soft% on the road. Although he runs well for a catcher, those sort of plays generally lead to routine outs, and even the best-case scenario is a measly single.

Something else to watch for moving forward: Realmuto gets slightly more “pull-happy” on the road. He sends 40.7 percent of batted balls to left field, an uptick from 38.9 percent when in Miami. All of his power is to that side and up the middle off the field, so pull percentage ought to be a strong indicator of whether he has his proper timing at the plate.

There are countless other factors to consider. Should he switch out the mattress at his house to wake up more refreshed each morning? Does a secret “road family” inspire him to work harder away from Marlins Park (a la Jose Reyes)? Is playing most home games with a closed roof throwing him off?

Even if these splits don’t change, Realmuto remains valuable to the Fish. In the meantime, though, maybe this needs to be part of the process that determines when second-stringer A.J. Ellis gets into the lineup.