Salvador Perez tore the Minnesota Twins a new one this week, racking up nine hits and hitting for the series cycle with two doubles, a triple, and a dong. You might not know it from all the attention paid to Jackie Bradley Jr.'s hitting streak, but Sal is riding a pretty nice one of his own, reaching in eleven straight games. To cap it all off, Perez even worked a five-pitch walk against Tyler Duffey to start the second yesterday afternoon, boosting his walk rate to a career high 4.8%. Eric Hosmer is clearly the offensive center of his team with a wRC+ of 133, but after last night's performance, Sal (123) has been deputized as his second, passing both Lorenzo Cain (114) and the shelved Mike Moustakas (118).
This season, Perez has been an extra-base hit machine, roping 11 doubles, 2 triples (!), and 7 homers, accounting for nearly half of the 45 hits that make up his .283 batting average. The key for Perez has been getting the ball in the air and limiting his ground balls.
Over the first five years of his career, Perez maintained a fairly standard batted ball profile with around 20% line drives, 45% ground balls, and 35% fly balls. This season, the line drive rate has been the same, but he has swapped enough grounders for fly balls that he is hitting the latter at more than a 50.8% clip, second highest rate in the league.
Batted ball type is judged by people watching the games, but this massive shift is also represented in the Statcast data available. A look at the batted balls recorded by the system shows his average launch angle has increased from 13.3 degrees in 2015 to 19.9 degrees this season. That's a pretty sizeable jump, as is his exit velocity, which is up from 87.9 mph to 90.6 this year. Perez has hit the ball in play or for a homer often enough that we can have some confidence this has been a real change, now the question is whether he can keep it up.
In some ways, Perez is still very much the hitter that he was when he lost his mind in 2014 and started swinging at everything. Perez has been a free swinger again this season, with a swing rate consistent with the last two seasons, both within and outside the zone. His swinging strike rate, however, is at a career high, and as luck would have it, the increase is due exclusively to missing on pitches outside the zone. Pitches outside the zone are tougher to square up, and making contact with fewer of them has taken away some of the more poorly struck balls that would have dragged his average exit velocity down last season.
In some cases, these additional swinging strikes have given Sal the opportunity to see a better pitch to hit, or take a walk, which he's now doing at a respectable rate. But it's also lead to an eight percentage point jump in his strikeout rate, bumping it up to 21.4%.
The contact rate on pitches outside the zone seems unlikely to continue. In a perfect world, Perez would swing at a 30%, rather than 40% of non-strikes, but that likely isn't in the cards. He'll probably hit a few more cans of corn and pound a couple more into the dirt, and his BABIP will regress, and he'll start hitting .260 again.
Sal Perez has always been a streaky player. Generally, hitters are, but Sal may be streakier than most. Just look at the 15-game rolling average of his offensive production for his career, again represented by wRC+. It reads like a train of pulses running through an active neuron. Perez is in a depolarization phase right now. He will repolarize, eventually, and then there will be a refractory period.
At the end of the day, Perez will likely be a league-average hitter, at least that's what the projection systems say the rest of the season has in store for him. That is better than he has managed the past two seasons though, and a league-average bat plays just fine with his defensive profile.