What’s wrong with Travis d’Arnaud?

After what appeared to be a breakout year in 2015, Travis d’Arnaud has taken a big step back in 2016. In 69 games, the catcher is hitting just .246/.300/.321 (71 wRC+), with four home runs, 14 RBIs, and 0.0 fWAR. That represents a steep decline from his production last year, when d’Arnaud hit an excellent .268/.340/.485 (130 wRC+), with 12 homers, 41 RBIs, and 2.3 fWAR in a nearly identical number of games.

What’s puzzling about d’Arnaud’s struggles is that his peripheral numbers haven’t changed all that much. As you can see from the chart below, his current BABIP is exactly the same as it was last year, while his strikeout rate is virtually the same as well. His walk rate is down a bit from his 2015 mark.

d’Arnaud’s approach does not appear to have changed much, either. His swing rates on pitches both in and out of the zone are nearly identical to what they were in 2015, and he is actually making more contact now. Likewise, d’Arnaud is pulling the ball at a similar rate as he did last year and is hitting the ball hard even more frequently. While his soft-hit rate is a bit elevated and while he is not using the opposite field quite as much, neither factor seems to account for his complete loss of power.

What stands out is how badly d’Arnaud is struggling to put the ball in the air. As the chart below illustrates, the catcher’s ground ball rate has increased by more than 15 percent. He is now putting the ball on the ground in more than half of his at-bats. Meanwhile, his line drive rate is down by about five percent and his fly ball rate is down by more than 10.

One might think that a change in d’Arnaud’s stance or swing could account for the loss of elevation on the balls he puts play. However, that does not appear to be the case. Compare the clips of d’Arnaud from last year to this year. His setup appears the same, he has the same quirk whereby he points his bat toward the pitcher, and his follow-through doesn’t seem to have changed. While there’s clearly an issue here, it’s hard to tell exactly what it is.

If there are no obvious flaws in d’Arnaud’s approach or swing that can be easily corrected, the question becomes what to do. It’s tempting to keep running him out there and hope he figures it out, because his ceiling is so high. But with two weeks left in the regular season and the playoffs potentially on the horizon, the team needs to come up with a plan.

Somewhat incredibly, d’Arnaud’s offensive production has been similar to Rene Rivera’s. Kudos to whoever predicted that in spring training. Rivera is hitting a meager .220/.292/.340 (70 wRC+), with five home runs, 24 RBIs, and 0.5 fWAR in 58 games. However, his defense behind the plate has been much better than d’Arnaud’s, evidenced by their 11-point difference in defensive runs saved (+5 for Rivera compared to -6 for d’Arnaud).

Another important difference between the two players has been their platoon splits. d’Arnaud (.261/.312/.359, 84 wRC+) has been much better against righties than has Rivera (.194/.248/.287, 42 wRC+). Rivera (.333/.459/.567, 177 wRC+), meanwhile, has crushed lefties, while d’Arnaud (.196/.262/.196, 32 wRC+) has struggled mightily against them.

These numbers are based on relatively small sample sizes, so take from them what you will. That said, given how stark their splits are, it might make sense for the Mets to platoon their two catchers, with d’Arnaud starting against righties and Rivera against lefties. Rivera can continue to catch Noah Syndergaard—regardless of who the opposing pitcher is—to help Syndergaard control the running game, which he has famously struggled to do.

The Mets can only hope that d’Arnaud’s struggles are an aberration. The promise he showed last year was so encouraging that the Mets appeared to have found their catcher of the future. Until he regains that form, however, the Mets will have to continue to mix and match behind the plate until they find a formula that works.