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J.T. Realmuto is still limiting stolen bases

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The Phillies catcher has only thrown out 14 base runners over the past two seasons, but he’s still done an excellent job of controlling the opposition’s running game.

MLB: Philadelphia Phillies at Atlanta Braves Dale Zanine-USA TODAY Sports

In 2019, J.T. Realmuto threw out 43 would-be base stealers in 92 opportunities, good for a 47% success rate. His 43 runners caught stealing led the league by a wide margin. It was arguably the most dominant performance from behind the plate in the past 20 years, considering his near 50% success rate and the sheer number of runners he threw out. That percentage – 47% – was cited in countless articles about Realmuto, and it was one of the driving factors behind the “best catcher in baseball” argument.

In 2020, however, Realmuto only threw out 5 would-be base stealers in 20 opportunities. That meant his caught stealing percentage (CS%) was just 25%, which was the worst CS% of his career. Could it be possible that the BCIB was all of a sudden showing major signs of decline at just 29 years old? Or could it all be chalked up to small sample size weirdness?

Well, it certainly wasn’t just a sample size issue. The same trend has continued into 2021. Realmuto has thrown out 9 of 34 would-be base stealers, which translates to a 26% success rate. Over the past two seasons combined (which adds up to one full season’s worth of games for Realmuto), he has thrown out 14 of 54, or 26%, of would-be base stealers.

But does it really make sense that J.T. Realmuto just lost his ability to gun down base runners? J.T. has a reputation for continually improving his game year after year. He’s only thirty years old, and he certainly doesn’t seem to be in physical decline based on his offensive statistics and sprint speed. While the league-wide caught stealing rate is somewhat lower in 2020 and 2021 (24.6%) than it was in 2019 (26.7%), that can’t explain Realmuto’s CS% dropping from 47% to 26%. So what is the explanation?

As it turns out, the answer is actually quite simple: base runners have learned not to risk it against J.T. Realmuto’s arm.

In 2019, runners attempted 92 steals off of Realmuto in the 1139.1 total innings that he was behind the plate. That’s 0.73 stolen base attempts per nine innings. In 2021, runners have attempted just 34 SB in 722 innings, or 0.42 SB attempts per nine innings. That’s a significant drop.

When runners are being more selective, it means they’re going to get caught less often. But that’s okay, because it also means that opposing base runners are stealing far fewer bases. In other words, Realmuto is still controlling the running game, he’s just doing so with intimidation tactics rather than powerful displays of arm strength.

Philadelphia Phillies v Atlanta Braves Photo by Todd Kirkland/Getty Images

Baseball Prospectus has a lot of useful catching metrics we can use to examine this a little closer. J.T. Realmuto ranks fourth among NL catchers this year in the metric TrCH, which measures “opportunities for stolen base attempts.” That makes sense, because he also ranks toward the top of the league in innings caught. However, despite having ample opportunities, runners tend not to attempt stolen bases against Realmuto. While he has the fourth-highest TrCH in the NL, his SrCH (which measures stolen base attempts) is only tenth-highest.

In actual stolen bases allowed, Realmuto looks even better. Twelve other National League catchers have allowed more stolen bases than Realmuto, even though only two have caught more innings than he has. Among NL catchers with at least 400 innings caught this year, only five have allowed fewer stolen bases than Realmuto. Of those five, only Yadier Molina has caught more innings than J.T.

Here is one more way to look at it. Over the past two seasons, J.T. Realmuto allowed 40 stolen bases in 1013 innings behind the plate. That's equivalent to 0.355 stolen bases allowed per nine innings. 21 other NL catchers have caught at least 400 innings in that time span. Only four have allowed stolen bases at a lower rate: Yadier Molina (0.236 SB/9), Curt Casali (0.275 SB/9), Elias Diaz (0.287 SB/9), and Buster Posey (0.303 SB/9). Casali and Diaz are defense-first journeymen, and neither is a full-time player. Molina and Posey are future Hall of Famers. Posey is the only one who is an above-average hitter. That’s good company for Realmuto to be in.

I think the Phillies fanbase will always miss the catcher we fell in love with in 2019. The one who gunned down 43 would-be base stealers, the most by a Phillies catcher since 1993. The one with the fastest pop time in major league baseball. The one who made us swoon with his caught-stealing wink. But that was never going to last. It was only a matter of time before opposing base runners caught on.

Without a doubt, Realmuto’s defense has been less exciting over the past two seasons. It’s a lot less fun without all the runners caught stealing. But rest assured, J.T. Realmuto is still an elite catcher when it comes to controlling the running game.