The evolution of the One-Knee Down Catcher

It matters which knee is down. Who knew?

It’s a bit early to start parsing cumulative season data and drawing inferences (small sample sizes, and all), so today will be a topic I picked up on during Spring Training.

Baseball can be such an interesting game. On the surface, it looks like grown men running around playing a little boy’s game, where pitchers pitch, hitters hit and the rest run to either catch up with the ball or race to home plate. Beneath this seemingly chaotic and disconnected action lies a symmetry that belies. Labor-of-love fans tend to appreciate the subtle complexity of the action, more orchestrated than appears at first blush. Today, I do a deeper dive on one of those intricacies only die-hard baseball fans could love. The catchers’ stance. Perhaps you’ve noticed that these have changed in recent years.

During spring training, I had an unanticipated opportunity to watch a one-knee down catching drill, up close, back on the 6-way bullpen down in Jupiter. What an experience. This caught my interest. I have noticed the recent evolution where now almost all the catchers are one-knee down on almost all pitches, all situations. Even to the point where they all set the target, remove the target, setting their glove in the dirt until just before the pitch arrived, and raise their glove to meet the pitch. The momentum of the glove raise would bring the ball and glove up a tick, which I inferred is part of the secret sauce of framing. This action moves the glove closer to the zone after receiving the pitch, in a natural, non-obtrusive way (ie. no snatching).

While I could see the evil genius in this, I found this odd (as in contrary to everything us old-schoolers were taught), because it also meant that while the pitcher was moving forward to release point, there would be no target to eye. I couldn’t hear the conversation at the pitching end, but I am gathering that their job was to throw to either the chest protector or belly button if they needed a target.

One of the drills, as described by the minor’s catching coordinator (nice to have one of those, huh?), was intended to make the catchers uncomfortable. I later learned the coordinator was named Goforth. The practitioners were to circle the intended pitch location with their gloves all the while the pitch was coming and meet the pitch at the last second. Essentially, wash-on, wash-off redux, 45 years later. Getting them used to having their glove perpetually in motion, as a steppingstone to dropping it on the ground and raising it. From watching, I gathered some of these guys probably grew up with old school high school coaches who taught framing as “setting the target”.

Interesting stuff. It was clearly time to do some more research. What I found early on is there is not a lot of research on this, and what research exists is mostly outdated because the trend has moved so fast from traditional to knee-down. Before 2020, knee down catching approaches were still unusual and most of the published articles were negative to the idea. Yet, by 2024, knee down occurs in 90% of all pitches. Mike Petriello published an article (link) on this topic during the 2024 post-season that is most up to date, containing 2024 season Statcast data. They determine knee up or down by measuring catcher knee heights. Who knew?

I recall as a younger fan, Cardinal catcher Tony Pena tended to catch in the one knee down posture, much to the great consternation of baseball glitterati. The old-timers are properly scornful of such modern antics that violate the time-tested practices of our own youth. Of course, old-timers are scornful of most anything they didn’t think of. Even Alex Rodriguez has been highly critical of one-knee down catching and he’s not even a catcher. Pena did win 4 Gold Glove awards, unsupported by a single metric more complicated than CS%. Now, 40 years later, everyone is doing it, and so similarly that it must be accepted and taught throughout all levels. Instead of stammering and sputtering about how the world is going to hell, let’s be curious and see if there is something to be learned here.

I’ll digress to a personal experience about being curious when time-honored truths are challenged. Years ago, as a younger firefighter, I got a chance to participate in a multi-day national training exercise on firefighting. It was really cool (in Indianapolis, of all places). In one class, my Captain told me to just be quiet and learn. Early on, the instructor provided some video and scenario information about a fire and picked on me (the new guy) by asking me what tactic I would use to attack said fire. I answered, violating my Captain’s orders to be quiet. The answer was obvious, but the question was a setup. The entire class of more veteran (mostly East Coast) firefighters erupted at my stupidity. Some even frothed at the mouth at my unbridled ignorance, expectorating their chew spit (not Zyn!) all over their walrus mustaches (which actually serve a safety purpose – a story for another day). The instructor, a scientist from Underwriters Laboratory – Fire Science Institute then spent the next two hours dissecting fire behavior with video and a plethora of heat sensors in real houses that they burned down just for this purpose. At the end of the day, the fulminating veterans were wrong, and not only wrong, but wrong in a way that kills firefighters. They didn’t care for his message, which was, you are here today not because you are good, but because you’ve gotten lucky. And those time-tested practices you’ve relied on all this time? Wrong. I learned (re-learned) that day that the curiosity we had as 5-year-olds is a good skill to retain, even if I think my experiences grants me the privilege to think I’m right.

Mark Twain once said “It Ain’t What You Don’t Know That Gets You Into Trouble. It’s What You Know for Sure That Just Ain’t So”

What is the knee-down catching stance, exactly?

This is probably dumbness on my part, but I really hadn’t caught on that there are 3 emerging knee-down stances. Left knee down, Right knee down, Both knees down.

In practice, a correct one-knee down stance leaves a catcher’s weight still well balanced between both legs. The straight (or kick-stand) leg is out front, with the foot pretty much even with the extended glove and both knees (one up, one down) have an even distribution of weight on them. This allows the catcher to maximize mobility. To achieve this balance, the catcher flexes towards the kick stand leg as the pitch starts its journey. The glove and both knees form a triangle of weight balance, where movement in multiple directions is supported. This “flex” reduces the catcher profile (theoretically improving the umpire view) and forces that balance of weight that improves mobility.

To go back to that drill I watched, I now infer that “circling” the glove is a “wash-on, wash-off” practice technique that gets catcher’s comfortable with maintaining that triangle of balance and also with catching the inbound pitch with the glove on the move. When I was a kid, we called it snatching at the ball, and coaches would fulminate and expectorate if we did it, just like those old fire-fighters. Gimme 10! Now knee down is a thing and setting the target is retro. In the bullpen and games, the Karate Kid Catcher eliminates the wash-on/wash-off glove movement, replacing with setting the glove on the ground and lifting in straight up to catch the ball. The final momentum of the glove brings the ball an inch or two up, into the K zone, without having that “snatching” effect on the umpire.

Does one knee down lead to more wild pitch/passed ball events?

By the numbers, the percentage of wild pitches and passed balls (PB & WP / G) per game is exactly the same today as it was when I was born in 1961. It oscillates over decades but remains relatively stable. If anything, the trend of this statistic has recently been down, during the time period the use of the one-knee down has become more commonplace than unusual. In 2024, there was 1 PB & WP event every 184 pitches. This is a lower rate than 2012, when there was a PB & BP event every 162 pitches. Rare either way, but clearly a positive trend, if you are a catcher. If anything, the suggestion is that one-knee down might reduce PB & WP events ever so slightly. But we will have to wait and see if it is improvement or just normal decadal oscillation in the data. For sure, it doesn’t make things worse.

Full disclosure, the WP & PB rate itself climbed a fair bit from 1920 to 1960, for reasons unknown, before stabilizing. It is fair to conclude that this plays no factor in one-knee down analysis, since we still have 60+ years of subsequent data to study. More to the point, the number of runs scored from 3rd base on WP & PB is the same today as it was in 1919. This further supports the old adage “…the more things change, the more they stay the same.”

If you aren’t convinced, gander at Baseball America’s take on this here.

As an editorial note, I’m going to hazard a guess that two-knee down stances really only occur when there are no runners on base, where WP, PB and SB outcomes aren’t possible. If I could get at the core Statcast catching data, I’d explore this but haven’t figured that out yet.

Does it improve pitch framing and strike/ball outcomes?

Start with this statistic from 2024. Strike rates for all pitches thrown to catchers in the two knees up position (the traditional pose I learned as a kid) was 45.6%

Strike rates for all pitches thrown to catchers in the one or two kneed down position varied from 46.2% to 47.8%, both a bit better than the traditional. The low is with the right knee down, the high is with the left knee down. All three statistics show that knee down stances result in improved strike rates (ie. improved framing). A marginal change, to be sure, but this is a game of inches after all. Think about it this way. A starting pitcher will throw in area of 100 pitches, and a team might be expected to throw more like 150 in total. With a left-knee down, you would expect there to be about 3 to 5 pitches that become strikes based on the marginal strike rate observed. Each game.

Here is the data. Knee code is 1) left knee down, 2) both knees down 3) right knee down and 4) traditional stance.

Tangotiger.com

Which knee should be down?

Some teachers will say that the knee that is down should be the knee that is on the same side as the shoulder the umpire is looking over, because that shoulder is then lower, giving the ump a cleaner view of the strike zone. Another ingredient in the secret recipe of pitch framing, I suppose.

The data says the left knee should be down to maximize strike rate, but I don’t have enough break down to know if catchers were choosing which knee down based on handedness of the batter or not. Stance aside, strike accuracy as a rule is lower with LH hitters, which would correspond to a slightly lower strike rate if catchers were right knee down. Ergo, the 1.6% strike variance from left knee to right knee down might be partially or fully attributable to the LH hitter factor as much as which knee is down. I think of this strike rate variance as the “Carpenter factor”, which seems to re-appearing as the “Nootbar factor”.

Interestingly, I’m not sure the Cardinals are teaching this way. These might be anecdotal accidents, but here are a couple of Cardinal videos. I found a snippet of Leonardo Bernal seeming to be opposite of all this. So maybe the teaching has evolved recently, or he is in learning mode, too. He was one of the guys in the catching drill I mentioned earlier. Note how he pushes the umpire up with his own upright stance. Bernal is a big dude, too. It appears (I need more visual data to be sure) that Bernal is expecting a steal here and perhaps right knee down gives him better pop time. Notice how he doesn’t really have a kick stand leg that is flexed, and his balance is more vertical and not triangular. I’d bet he would struggle with a pitch in the dirt here. Also, note that he subtly raises to a two-knee up stance as the pitcher comes forward. Statcast might still evaluate this as a two-knee down stance all the way, as I think anything with the knee measured as 9” or closer to the ground is considered “knee down”. But he definitely shifts back to what I suspect is the more natural and comfortable two-knee up stance mid-pitch. I suspect the one-knee down thing is a work in progress for him. See for yourself (watch the catcher from beginning to end, ignore the play).

Below is what I suspect the final product is intended to look like. Much better balance, much lower setup (improving the umpire view?), although the knee is still down opposite what the methodology says it should be. Hmmm. More research to do, I guess. Same advice here, watch the catcher from beginning to end, not the play.

As a side note, if you wonder how far away L. Bernal is from being an MLB-ready receiver, you might view these two catchers side by side and that might provide at least part of an answer. A lot of his game (bat, throwing, etc.) seem almost ready now. But receiving, I’d say he looks more like a HS catcher than an MLB catcher. This isn’t meant to be harsh or judgmental, just a reflection of modern catching development having to undo years and years of “old school” catching approaches. Old habits die hard.

How does it impact catcher pop times?

It seems the data is yet unclear on pop times so far. There is a theory here that makes sense, however. That is, every pitch is a framing opportunity, but not nearly every pitch is a base stealing (ie. pop time) event. The coaching philosophy has evolved that even if there is a sacrifice in pop time, they more than make up for it in framing improvement, just because the volume strike/ball events is so much greater than the volume of stolen base attempts.

Earlier, the math illuminated that the impact of one-knee down perhaps results in 3 to 5 more strike calls over the course of a game. If a catcher were to move to the 2 knee up position for base stealing situations (on the theory that 2 knee up gives them the best pop time), they’d do so for ~50% of the pitches in a game and would then likely lose 2 to 4 strikes per game. Ask your pitcher. Do you want 2 to 4 more strike calls or do you want a .1 improvement in pop time in case the other team runs? Remembering that a typical caught stealing percentage is around 20%. What is the run value of a .05 second pop time improvement on a base stealing attempt versus 2 to 4 balls becoming strikes. What do you suppose the answer from the pitcher would be?

Can 2-knee down-catching eliminate pop time?

I couldn’t find any data on this, although I did find training videos encouraging knee down catchers to just throw from their knees. They lose a bit of velocity but gain by totally eliminating the pop-time portion of throwing. A catcher with arm talent can get the ball to second base accurately quickly throwing from his knees, based on video I saw. We certainly have personal history with throwing to first from the knees, as Molina perfected that throw on back-picks to first base where Pujols stood. I have really no idea of the rate that MLB catchers are throwing from the knees, or if it is intentional or just a by-product of pitch location.

I expect 2025 will be a local experiment on this very approach involving our heavy hitting catcher, Ivan Herrera. We will all learn about this together.

Conclusion

Everyone is doing it, so it must be right. Right? The data signal is pretty strong, although a few more years of data will help solidify. One thing is for certain. There is no strategic advantage here, since everyone is pretty much doing the same thing. I’ll circle back on this one someday.

When I return to this topic, I hope to be able to see how the ABS/strike challenge system has influenced ball/strike calls. In theory, ABS should reduce if not eliminate the benefits framing has on strike rates. Will that tangentially influence the perceived benefits of a knee-down stance?