The Twins’ Two-Headed Catching Monster

It’s a rough time to be a catcher. Over the last couple of years, we’ve seen catcher offensive production drop to extreme lows. Last year, major league backstops compiled 49.9 WAR, the lowest total since 2004, and their collective wRC+ was just 84, the lowest mark since 2002. In this day and age, it’s not uncommon to see teams select their starting backstops based on their defensive prowess and ability to handle a pitching staff rather than their ability to contribute offensively. That’s the only explanation for why Jeff Mathis continues to receive plate appearances despite a running a wRC+ that’s in the single digits.

For most teams, the backup catcher is an afterthought on the roster, selected for his ability to competently go about his duties without hurting the team too much. Most backup catchers see the field once or twice a week, three times if they’re lucky, so their effect on the overall production of the lineup is rather minimal. But there are a few squads this year who have been blessed with an abundance of catching riches.

Five teams have received more than three wins from their catching corps in 2019:

Team Catching, 2019
Brewers 113 29.35% 17.6 4.6
Phillies 97 40.48% 6.5 4.2
Diamondbacks 109 40.38% 9.4 3.8
Twins 116 21.54% 3.7 3.8
Red Sox 84 31.88% 14.4 3.1

For the Brewers, Phillies, and Red Sox, their primary backstop has provided the majority of the production. The Diamondbacks have two catchers on their roster who have been worth more than a win each (the Mariners and the Dodgers can also claim this feat, though the cumulative WAR total for their catchers isn’t as impressive). Like Arizona, the Twins have a good catching tandem, an especially nice development after struggling to find a successor to Joe Mauer behind the dish.

Jason Castro is playing the role of the veteran backup, though the playing time split has been closer to a 60-40. Back in June, my colleague Sung Min Kim did an excellent job of breaking down the swing changes Castro has made over the last few years to maximize the batted ball quality he’s creating:

Castro is hitting the ball harder and higher than he previously has in the Statcast era. We’ve known Castro as a solid starting catcher over the years. He was an All-Star back in 2013 and was a part of the Houston Astros core for their dreadful years (and a couple of winning seasons). But he wasn’t a guy known for his offensive prowess.

He’s continued to hit the ball hard, though his overall offensive contributions have slipped since Kim’s article. Still, between his 113 wRC+ and his solid defense behind the plate, he’s been worth 1.6 WAR this year, 11th among all catchers who have made at least 200 plate appearances. That puts him ahead of the top catcher for two-thirds of the teams in the majors.

But the real success story has been Mitch Garver’s emergence. Garver was a ninth-round draft pick back in 2013 and made his major league debut in 2017. His offensive skills outshone his defense as a prospect, which remained true after reaching the highest level of competition. He was thrust into a full-time role last year after Castro injured his knee in early May. Offensively, his 102 wRC+ ranked 10th out of all 27 catchers with more than 300 plate appearances. But all of those contributions beside the plate were wiped out by his ineptitude behind it.

Fast forward a year and Garver has improved across the board. After blasting home runs in each of his last two games, he’s pushed his slash line up to .266/.346/.614, good for a 144 wRC+. That’s comfortably the highest mark among major league catchers, and the 16th highest mark among batters with at least 250 plate appearances. Those two home runs have also pushed his season total up to 23 — his previous career high was 17 in 370 plate appearances in Triple-A back in 2017. His isolated power during that season was .250; it’s up to .348 this year, the fourth highest mark in the majors.

As you’d expect, Garver has improved all the right batting peripherals. His average exit velocity is up a couple of ticks, his launch angle is up by three degrees, and his hard hit rate sits in the 91st percentile. He’s added more than 10 points to his fly ball rate and more than a quarter of the fly balls he’s hit have left the field. His 96.6 mph exit velocity on fly balls and line drives places him in the 94th percentile for that metric. He’s simply crushing the ball when he hits it in the air.

All that extra offense is impressive but he’s also improved behind the plate, too. Last year, he was one of the worst defensive catchers in the league. Over the offseason, Garver committed to making improvements to his ability to receive the ball behind the plate. The results speak for themselves:

Mitch Garver, Framing Runs, 2018-2019
Year FRM CSAA Shadow Zone Strike Rate
2018 -10.1 -8.2 42.0%
2019 0.4 1.9 47.6%
CSAA = Called Strikes Above Average, per Baseball Prospectus; Shadow Zone Strike Rate per Baseball Savant.

He hasn’t turned himself into an elite defensive catcher by any means, but just getting to average has helped him erase a big black spot on his ledger. It’s helpful that all three framing metrics agree that he’s made some significant improvements this year. Looking a little closer at the Statcast framing metric, we see that he’s really improved his ability to earn a called strike on low pitches. The league average conversion rate at the bottom of the strike zone is around 50% but he’s converting 55% of those strikes this year, up from a terrible 33.7% last year.

Twins catchers have posted the second best offensive line for the position group. (Only a disappointing 68 wRC+ from Willians Astudillo is bringing down their overall contribution.) What makes the catching tandem of Mitch Garver and Jason Castro even more potent is their perfectly aligned platoon splits:

Twins Catchers, Handedness Splits
Player Split PA BB% K% ISO wRC+
Mitch Garver vs RHP 168 7.1% 28.0% .318 122
Jason Castro vs RHP 170 9.4% 28.8% .293 131
Mitch Garver vs LHP 90 14.4% 21.1% .392 185
Jason Castro vs LHP 34 11.8% 29.4% .000 21

Castro is practically inept against left-handed pitching but thrives when holding the platoon advantage. Garver’s platoon split is a little less pronounced — he’s crushed opposing pitching no matter what hand they throw with — but he’s definitely been better against lefties. That’s allowed the Twins some flexibility if they want to get both catchers into the lineup or have Garver pinch hit for Castro if the opposing team brings in a tough lefty reliever.

In the five seasons since Joe Mauer’s last season behind the plate in 2013, Twins catchers have accumulated a combined -0.4 WAR. This year, they’ve accumulated 3.7 WAR, and their catching tandem is still going strong. Castro is a free agent after this season, but Garver’s development into an offensive monster to go along with his improved defense should solidify this position in Minnesota for years to come.

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Jake Mailhot is a contributor to FanGraphs. A long-suffering Mariners fan, he also writes about them for Lookout Landing. Follow him on Twitter @jakemailhot.

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Garver is a pleasure to watch hit. He’s not flashy, but he has a short swing and understands what the pitcher is trying to do to him. He doesn’t chase or swing and miss. ISO 60 points higher than Sanchez. I’m curious to see if he can maintain a high WRC+ with more PA next year.