Does One-Knee Catching Actually Lead To More Wild Pitches?

Image credit: (Photo by Frank Jansky/Getty)

Last night, ESPN analyst Alex Rodriguez watched Travis d’Arnaud set up in a one-knee stance with a runner on third and noted that he worried that such a stance would leave the Braves catcher vulnerable to a ball getting away.

“You see his knee on the ground. I don’t like this,” Rodriguez said. “(Will) Smith’s slider has been his problem. Any ball in the dirt could cost you a run. With one knee on the ground, you limit your movement, your range of motion.”

On cue, Will Smith‘s slider was buried in the dirt. But instead of it getting away, D’Arnaud blocked it well.

This is not only a viewpoint held by Rodriguez. There are many in and around baseball who view the steady movement toward one-knee setups as a dangerous tradeoff. To summarize the argument, the risk of passed balls and wild pitches, as well as a lessened ability to throw out basestealers, may not be worth the potential benefit in better framing of borderline pitches.

There have always been some catchers who were comfortable going to one knee in their setup. The incredibly agile Tony Pena was one who adopted all sorts of acrobatic setups when he received. But the steady rise of the one-knee receiving approach recently stems from adopting it to better frame and present pitches, especially at the bottom of the zone.

Tanner Swanson, a coach at Washington, brought the one-knee setup to the Twins when he was hired before the 2018 season as the team’s minor league catching coordinator. The Yankees hired Swanson as their major league catching coordinator before the 2020 season.

We’re not going to study whether the one-knee approach pays off in better catcher framing ability. That’s subject for a different study. What we wanted to look at today is whether Alex Rodriguez (and others) are right. Does a one-knee approach leave teams vulnerable to wild pitches, passed balls and stolen bases?

To get a better idea of what the potential tradeoffs are, we classified every catcher who had 20 or more games caught in the majors in 2020 by their setup. While it would have been potentially helpful to classify every catcher, selecting the 54 catchers with 20 or more games limited the amount of time spent on classification and allowed us to focus on catchers who were regulars or regular backups in the major leagues. There were 898 games in the Major League Baseball regular season last year with 15,468.2 total innings. This study looked at 12,843 innings caught, so it accounts for 83% of all innings caught last season.

We looked at multiple sliders out of the zone for each catcher—both with runners on and with no one on base—to see how they set up to receive.

Each catcher was classified in one of three ways.

Some use the one-knee setup, where their catching stance has them receiving the ball with one knee on the ground (and usually the other leg kicked out in a straight-leg pose). A one-knee setup is one like this, as shown by Twins catcher Ryan Jeffers.

Others have what we would describe as the conventional catcher crouch, with both knees off the ground, squatting. That setup is demonstrated by A’s catcher Sean Murphy.

There is a third setup. Some catchers use a hybrid approach. With no one on base, they use a one-knee setup to try to present pitches better for the umpire. But when a runner gets on base, the catcher will go back to a conventional setup because they feel it better allows them to block pitches in the dirt and throw if a baserunner attempts to steal.


There is almost a perfect split between the two styles. Of the 54 catchers, 22 were classified as using a conventional setup, and 21 were using the one-knee setup. Another 10 used the hybrid approach. One, Chance Sisco, was too unpredictable to be classified and so his data was not used.

Some catchers were a little difficult to categorize. With runners on, Will Smith seemed to adopt a conventional setup, but with the pitch on the way, he dropped a knee to adopt the one-knee stance. He’s classified as a one-knee catcher.

Yan Gomes would occasionally adopt a one-knee setup, but in the pitches surveyed, he much more often adopted a conventional setup, so he’s classified as conventional.

Jorge Alfaro is even tricker to define. He would set up conventionally, but usually dropped his knee as he caught the pitch. He’s classified as conventional, as he did not appear to be using the knee in his setup and only used it at the point of receiving.

Chance Sisco‘s setup varies enough as to defy categorization. He adopted a conventional setup at times and a one-knee setup at other times with no runners on. Cam Gallagher usually adopted a conventional setup, but there were other times he’d drop one knee. He’s classified as conventional since that seems to be his more common approach.

The goal of this quick study was to see if there was any clear degradation in pitch blocking or throwing among catchers adopting the one-knee setup.

The first thing to note is that at the major league level, the amount of borderline pitches a catcher receives is significantly larger than the number of balls that get away from even the worst MLB receiver. Catchers receive around 140-150 pitches per game, 

The catchers studied as a whole allowed one-half of one wild pitch and passed ball per nine innings played. Similarly, the catchers saw two-thirds of one stolen base attempted per nine innings played. Stolen bases, wild pitches and passed balls are all rather rare events in MLB at this moment.

What the study found is that there did appear to be a minor benefit in wild pitches and passed balls for conventional setups vs. the one-knee approach. Conventional setup catchers allowed .432 wild pitches and passed balls per nine innings. Catchers with a one-knee setup allowed .466 wild pitches and passed balls per nine innings.

But there’s one other complicating factor. The worst blockers were catchers who adopted the hybrid approach. They allowed .560 wild pitches and passed balls per nine innings. With runners on base, they could be reasonably classified as adopting the conventional setup—the only time a catcher can give up a wild pitch or passed ball with no one on base is on a strikeout where the batter reaches. If you add these hybrid receivers to the conventional setup receivers, the conventional receivers would have an average of .473 wild pitches and passed balls per nine innings, which is slightly worse than the one-knee receivers.

What about basestealing? Now, this study doesn’t control for arm strength, pitchers ability to hold runners or quality of baserunners, so it makes plenty of assumptions that could add noise to the result.

But taken just on its own, conventional receivers threw out 24.9% of basestealers. One-knee setup catchers threw out 26.2% of basestealers. The hybrid receivers were the worst with a 22.7% caught stealing rate. The one-knee receivers and conventional receivers faced an almost identical rate of stolen base attempts (.689 attempts per nine innings for conventional receivers and .680 attempts per nine innings for one-knee receivers while hybrid receivers faced .640 attempts per nine innings).

So the data seems to indicate that one-knee receivers aren’t sacrificing any significant amount of ability to handle wild pitches or passed balls. They aren’t giving up more stolen bases either.

But what it also indicates is that catchers who try to “split the difference” may be penalizing themselves and their teams. It’s possible that the catchers who adopted a hybrid approach are significantly worse blockers and throwers than the other catchers (that’s outside the scope of this study), but it’s also possible that by attempting to use two different setups, they aren’t doing as well at either.


Here is how all 54 catchers were classified, which may prove useful for those who want to study this further.

Catcher Team Setup
Alex Avila MIN One-Knee
Andrew Knapp PHI Conventional
Anthony Bemboom LAA Conventional
Austin Barnes LAD Conventional
Austin Hedges 2-TM One-Knee
Austin Nola 2-TM One-Knee
Austin Romine DET One-Knee
Cam Gallagher KCR Conventional
Carson Kelly ARI Conventional
Chadwick Tromp SFG One-Knee
Chance Sisco BAL Not consistent
Christian Vazquez BOS One-Knee
Curt Casali CIN Hybrid
Danny Jansen TOR Conventional
Drew Butera COL Conventional
Elias Diaz COL Hybrid
Gary Sanchez NYY One-Knee
J.T. Realmuto PHI One-Knee
Jacob Stallings PIT Conventional
James McCann CHW Hybrid
Jason Castro 2-TM Hybrid
Jeff Mathis TEX Conventional
Joey Bart SFG Hybrid
John Ryan Murphy PIT Conventional
Jorge Alfaro MIA Conventional
Jose Trevino TEX One-Knee
Kevin Plawecki BOS One-Knee
Kurt Suzuki WSN Conventional
Luis Torrens 2-TM One-Knee
Martin Maldonado HOU Hybrid
Max Stassi LAA Conventional
Michael Perez TBR One-Knee
Mike Zunino TBR Hybrid
Mitch Garver MIN One-Knee
Omar Narvaez MIL Conventional
Pedro Severino BAL Conventional
Roberto Perez CLE One-Knee
Robinson Chirinos 2-TM Conventional
Ryan Jeffers MIN One-Knee
Salvador Perez KCR One-Knee
Sandy Leon CLE Conventional
Sean Murphy OAK Conventional
Stephen Vogt ARI One-Knee
Tony Wolters COL Hybrid
Travis d’Arnaud ATL Hybrid
Tucker Barnhart CIN Hybrid
Tyler Flowers ATL One-Knee
Victor Caratini CHC Conventional
Will Smith LAD One-Knee
Willson Contreras CHC Conventional
Wilson Ramos NYM One-Knee
Yadier Molina STL One-Knee
Yan Gomes WSN Conventional
Yasmani Grandal CHW Conventional

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