Bad Plate Discipline Is Not Working Out for Salvador Perez

It just hasn’t been Salvador Perez’s season so far. He missed the Royals’ first 20 games with a Grade 2 MCL tear in his left knee, which he sustained while carrying luggage. Perez responded well upon his return, posting an .840 OPS over his first 11 games and even catching both games of a doubleheader just four days after getting activated.

Since then, Perez has been hampered by a different type of baggage. Over his last 54 games, he has been batting .194 overall and just .201 on balls in play. His xBA over that period, according to Baseball Savant, is .257, but that doesn’t mean that Perez’s fantasy owners should just sit back and enjoy the positive regression to come. Over last month, encompassing 101 plate appearances, Perez has batted .163 with one home run and three doubles, and his hard contact rate has been a pedestrian 34.7 percent.

Perez has a history of wearing down in the second half, and he may be getting a head start on that trend this season. Between 2014 and 2017, Perez posted a .336 wOBA in the first half, but that mark dipped to .272 in the second half. As is typical for him, he has been playing frequently. Perez has started all but one of the Royals’ 66 games since his return, and he has started at catcher for 26 of the team’s last 31 games.

Whether Perez is wearing down earlier than usual, still feeling the effects of his early-season knee injury or just plain slumping, it’s coming at a particularly bad time in his career arc. If he is slumping, it may be because of where he is at in his career arc. Perez has never been a choosy hitter, but his plate discipline has been especially bad the last two seasons. As the table below shows, he has increased his O-Swing% substantially this year, just as he did last year. Possibly because pitchers know they don’t have to give Perez pitches in the strike zone, his Zone% has fallen precipitously, especially from 2017 to 2018.

It’s a trend that is working against Perez, because he has the lowest wOBA on pitches outside of the strike zone (marked here as O-wOBA) of any hitter this season (min. 100 plate appearances on pitches out of the zone). Perez (.173), Chris Owings (.189) and Alcides Escobar (.196) are the only hitters with a sub-.200 O-wOBA.

Given that Perez’s plate discipline has been worsening, it’s not surprising that he has been an especially bad hitter on bad pitches. The graph below shows that more selective hitters tend to be more productive than unselective hitters when they do offer at pitches out of the strike zone. The greener the dots, the higher the O-wOBA, so you can see that selective hitters like Joey Votto, Brett Gardner and Shin-Soo Choo hit well when they venture out of the zone. (Interestingly, the lone green dot in the sea of red on the right belongs to Eddie Rosario, who is making bad-pitch hitting work for him.) Players with dark red dots are highly unproductive when swinging at pitches out of the zone, and no one is doing that at a higher rate than Perez.

While the relationship between the frequency of swings at bad pitches and the level of production on bad pitches is clear, it is odd to notice that Javier Baez — who is having a breakout season — is keeping Perez company on the extreme right side of the graph. Like Perez, Baez swings at approximately half of the pitches he sees outside of the strike zone, yet he doesn’t seem to be paying a price for it. Baez (.234 O-wOBA) has not been good on pitches out of the zone, but he’s been a bit better than Perez. What really separates them is how well they hit on pitches in the strike zone. With a .342 Z-wOBA, Perez has been mediocre, but Baez has the sixth-highest mark (.454) in our sample. The Cubs’ star infielder can overcome his poor plate discipline by being a superb hitter when he does offer at pitches in the zone.

Even halfway through the season, it’s hard to sit players like Perez, who were frequently drafted within the first 10 rounds in standard mixed leagues. Maybe Perez has hit bottom. Maybe he has some BABIP regression coming his way. It’s probably not a good idea to assume either of these things. With the hottest part of the summer yet to come, Perez could have yet another season with a second-half swoon. Given the trajectory of his plate discipline, that seems more than just plausible. Perez does not have a history of being a great hitter on pitches that are in the strike zone, and it seems unlikely he will find success via that route now, like Baez has.

I own Perez in a 15-team mixed Great Fantasy Baseball Invitational league, and while I am not ready to drop him, I will look to bench him in favor of a waiver option like Robinson Chirinos or Elias Diaz. Perez is also worth benching in shallower formats, where catchers like Tucker Barnhart and John Hicks may be available.