A backup catcher is usually one of the least exciting players on a roster. The prototypical profile is simple: a capable defender behind the plate, but an easy out in the batter’s box. There aren’t many starting catchers who can actually hit, so those who are No. 2 on a depth chart are usually inept offensively.
That wasn’t the case for the Astros in 2021.
Jason Castro returned to Houston last season after leaving in free agency following 2016. The Astros’ first-round pick of 2008 signed a two-year contract, which looks to be a savvy move by the club considering what happened in year one.
2021 saw Castro produce some of the best numbers of his career, highlighted by a quality .235/.356/.443 slash line and 8 home runs. A .799 OPS and a 123 wRC+ were the best marks the 11-year veteran had posted since his All-Star campaign of 2013. Only six catchers finished 2021 with a better wRC+. That is, those who accrued at least 170 plate appearances.
Despite his tremendous offensive output, the lefty-swinging Castro received just 179 plate appearances, making a paltry 37 starts all year. This was through no fault of his own, as Martín Maldonado’s purported wizardry behind the plate kept Castro in a bench role.
Maldonado was perhaps the worst hitter in baseball in 2021 (63 wRC+), but his defense and unquantifiable impact on the pitching staff earned him the lion’s share of playing time. Castro, however, is no slouch defensively — he’s regularly graded as a solid or better framer since 2015 and has over a decade of catching experience in the major leagues.
The 35-year-old Maldonado is armed with a cannon throwing arm while Castro is not, but it’s not terribly important in the grand scheme of things — Castro’s offensive prowess and reliable glove more than make up the difference, plus the general de-emphasis of stealing bases in recent years helps as well.
Additionally, for what it’s worth, Castro was roughly one win better than Maldonado in terms of WAR according to both fWAR and bWAR, despite garnering 247 fewer plate appearances.
Putting aside the comparison, Castro has become an awfully impressive hitter, and not just for a catcher.
It began in 2019 with the Twins, a year that saw Castro produce an incredible 17.2 percent Barrel rate, putting him in company with the likes of Mike Trout, Aaron Judge and Yordan Álvarez. Though it came in only 275 plate appearances — due to another offensive explosion by the other Twins catcher, Mitch Garver — Castro’s 2021 data reinforced what he did in 2019.
Unsurprisingly, Álvarez led the Astros in Barrel rate and Blast rate, but in a lineup littered with All-Stars, it was Castro who ranked second in each category, per Alex Chamberlain’s Pitch Leaderboard. Overall, the wide discrepancy in plate appearances notwithstanding, Castro’s xwOBA rivaled any of his teammates’.
A clear three-true-outcomes slugger, the 34-year-old backstop produced the highest walk rate (14 percent) of his career in 2021 while concurrently lowering his strikeout rate to a manageable 30.2 percent. However maligned TTO hitters may be by writers and fans in the “old-school camp,” it’s a luxury for any team to have a catcher capable of generating meaningful numbers.
Castro might not have the durability to sustain a starter’s workload throughout a whole season — discomfort in his right knee forced him to miss four weeks last year, and more notably he’s long had issues with that particular knee since tearing its ACL in 2011 — but he has legitimate two-way ability. 37 starts or 179 plate appearances — however sliced — is far too few for a player who can be a key contributor.