Catchers Who Could Be Hurting Pitcher Performance

I know you've probably gotten used to me taking to these virtual pages to talk about the value of catchers. As a former catcher, it's become my good-natured crusade to get you to believe that catchers matter for fantasy baseball and are worthy of your thoughts and attention. However, sometimes that can be true without always being positive.

On an early episode of my podcast Catcher's Corner (check it out on Apple, Spotify, etc.) my co-host, Sami Akleh, and I analyzed Chris Paddack's first start and the confounding reality that he only threw two types of pitches the entire time. One of the points we discussed was that Paddack was a pitcher who was struggling with confidence and was paired with Luis Campusano, a catcher who had played one major league game up to that point. We both believed that Paddack needed a strong veteran presence behind the dish to instill confidence in him through having an understanding of when and where to throw all of his pitches.

This brings us to the premise of today's article which is simply: the guy behind the dish can have a major impact on the performance of a starting pitcher. On the surface, we all understand this as a concept; however, we never really talk about it or factor it into our decision-making when it comes to start/sit or trade decisions. It's time we change that.

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Rationale

Even if we can't lock in 100% on WHY these splits exist, it's important to take note that they do. Sometimes we can pick up clear differences in pitch mix from each catcher. Sometimes pitchers simply don't feel comfortable with a certain catcher because of the way they call a game, their ability to handle a pitch in the dirt, or the way they frame or give a target. However, if we have a big enough sample size of data, we need to start using that in our decision-making.

Below, I'm going to cover a few pitchers who have noticeable results splits depending on who is behind the plate. We'll look not just at deserved ERA (dERA) but also barrel rates, swinging strike rates, CSWs, and overall differences in pitch mix. However, it's important to keep in mind that I'm using stats to make educated guesses. 

I have not gone back and watched every single start for these pitchers. Maybe a pitcher had an off night. Maybe some of the pitches were good, but the hitters were just better that night. If a pitcher below may be on your team or something I'm suggesting catches your eye, I'd encourage you to go back through the play-by-play of certain games (looking at all pitches in each at-bat), watch the replay of the game, or simply keep an eye on it the next time out. Then this information can be used as a piece of a larger puzzle.

All of these charts are courtesy of Alex Chamberlain's awesome Pitch Leaderboard resource. I highly encourage you to check it out. 

Shane Bieber, Cleveland Indians

I know that Bieber is now on the IL with a shoulder injury, but even before that took place, something stood out to me. Bieber was a decidedly better pitcher when Roberto Perez was behind the plate.

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Since Bieber is the first pitcher we're looking at, let's make sense of these numbers a bit. Perhaps most importantly, we need to check his deserved ERA (dERA), which Alex Chamberlain's table calculates by isolating the work of the pitcher separate from the quality of opponent, park factors, etc. While this can often be impacted by whether a pitcher is having a "good night" or has a feel for certain pitches are not, Bieber has thrown a similar number of pitches to both Austin Hedges and Roberto Perez, so the fact that Bieber's dERA is over two runs better with Perez is meaningful.

The barrel rate between starts with Hedges and Perez is also different, as is the deserved hard hit rate (DHH%) and average exit velocity, which are both higher with Hedges at catcher, so it's clear that Bieber is giving up more consistent hard contact with Hedges behind the plate. We can also look at the swinging strike rate (SwStr%) and whiffs per swing (Whiff/Swing) and see that Bieber has been generating more swings-and-misses with Perez calling pitches. So these numbers all seem to imply that Bieber gives up less hard contact and misses more bats when Roberto Perez is his battery mate.

Let's see if that's true on a baseline stat level as well. Roberto Perez fractured his finger on April 13th but played through the injury before being put on the IL the first week of May, so Bieber's stats during March/April should be different than his starts in May and June.

Every important baseline metric was better during the beginning of the year than post Roberto Perez injury. Now, Perez has been Bieber's catcher for a few years now, so a lot of this could have to do with comfort and trust; however, if you look at how these two catchers call a game, you can also spot some differences.

Hedges goes to the curveball more overall, but he also uses it as the primary out-pitch with Bieber on the mound. While the pitch still performs well with Hedges, you can see that the dERA is two runs higher, the SwStr% is 4% lower, and the CSW is 8% lower. So even though the fastball has a low SwStr% and isn't Bieber's best swing-and-miss pitch, it's possible that Perez using it more often, especially with two strikes, is actually setting the curve up for more success.

I've discussed at length how pitches don't exist in a vacuum. Sometimes a pitch is successful because of how it pairs with another pitch, so simply throwing a good pitch more won't always lead to more success with that pitch. That might be the case here. We can also see that Perez goes to the slider more with two strikes than Hedges does, and the slider performs drastically better with Perez catching in both SwStr% and contact rates. In fact, Bieber hasn't given up a single barrel on a slider while throwing to Perez but has a 6.5% barrel rate with Hedges.

Now, as I mentioned above, we'd need to watch every pitch to be able to say definitively WHY Bieber pitches better with Perez behind the plate, but this shows us that he does. With Perez expected back in July, it's possible that his return to the Indians could coincide with Bieber's return from the IL and be an added tonic for the beleaguered ace. To me, that means Bieber could be a good buy-low candidate if somebody in your league thinks the problems are piling up. Perhaps he just misses his battery-mate.

Luis Castillo, Cincinnati Reds

Luis Castillo is another ace who struggled out of the gate and sent us all searching for answers anywhere we could find them. Perhaps one of the pieces of the puzzle was simply looking at who was behind the dish.

Interesting. A couple of things jump out: the dERA and DHH% with Tucker Barnhart behind the plate are much higher. I mean, that's an 11.3% difference in deserved hard hit rate; that's huge. I also notice that the SwStr% and Whiff/Sw metrics are much higher when Barnhart is behind the plate, and there's a difference of almost two inches in vertical movement, so maybe he has a pitch mix that is more designed for getting swings and misses but leaves Castillo open to harder contact.

Two things stand out to me from the start. One is that Tyler Stephenson uses the fastball more often, both with two strikes, but also overall (even though we can't tell exact numbers from this chart; we can at least see the pitch tendencies). Interestingly, the four-seamer performs similarly as a swing-and-miss pitch for both catchers, but has a far superior dERA when Stephenson is calling pitches and a much better barrel rate and DHH%.

Considering there is slightly more total movement on the pitch when Stephenson is behind the plate, it's possible that he is getting Castillo to use the pitch more at the top of the zone, which would make sense with higher usage of the pitch with two-strikes. Since we know the difference in vertical movement often leads to better "stuff" metrics, this is an important thing to keep an eye on.

I also notice that Barnhart uses the sinker more than Stephenson does, both as a regular pitch and with two strikes. Then I look over and see that the sinker has a 11.93 dERA with Barnhart and 1.36 dERA with Stephenson and think that the younger catcher appears to be much better at deploying that pitch or choosing not to. In fact, it's yet another pitch that has move overall movement with Stephenson behind the plate, so this may be a case of Stephenson changing eye levels a little more than Barnhart and sequencing pitches less for strikeouts but more for outs on balls in play.

Since we also know that Castillo has been struggling this year at getting swings and misses in two strike counts, it seems that tailoring a pitch mix to go away from focusing on punchouts and more towards softer contact (almost four MPH difference in exit velocity) makes more sense overall.

I know many people are focusing on the difference in the weather when it comes to Castillo or maybe that he was simply adjusting to the new ball, and I don't mean to suggest the catcher he throws to is the main factor in his slow start; I'm simply suggesting that it might also be part of the puzzle.

Sonny Gray, Cincinnati Reds

Castillo's teammate finds himself in a similar situation; however, for slightly different reasons. In this instance, games with Barnhart behind the plate allow for more vertical movement (because he uses the fastball more), but the dERA, barrel rates, and DHH% are still higher than when Stephenson catches. Here we also see another instance in which the SwStr% and Whiff/Sw are higher with Barnhart, but the difference is not quite as large as it was with Castillo.

The first thing I see here is that the four-seamer is more prominent when Barnhart calls games; however, it also performs worse with a dERA of 8.54 compared to 3.79 when Stephenson is calling pitching. Stephenson also gets more movement on the fastball overall, which means he's likely using it in different areas of the plate and likely higher in the strike zone. We also notice that Barnhart likes to use the slider a little more, especially with two strikes, and it's been a solid pitch for Gray in those games, which a massive difference in SwStr% and Whiff/Sw.

However, the biggest difference here is in the usage of the curve. When Stephenson is behind the plate, Gray uses the curve more than any other pitch, but it is the fourth most-often used pitch when Barnhart is behind the plate. The curve is also much better when Stephenson is calling pitches and is actually Gray's best pitch by SwStr% overall on the season. While the slider is also a good swing-and-miss pitch, Stephenson is able to use the curve early in counts as well, inducing a fair amount of groundballs and a lower dERA.

The stats would also imply that using the curve earlier in counts allows Gray to be more deceptive with it with two strikes, since the SwStr% and Whiff/Sw are higher with Stephenson catching. Since Stephenson has almost twice as many innings catching Gray as Barnhart, the numbers may be unfairly weighted, but the drastic differences in pitch mix make me think that this is something to keep an eye on going forward.

Austin Gomber, Colorado Rockies

First, let's get the Coors argument out of the way because, surprisingly, Coors actually hasn't been an issue for Gomber.

Now, we know that Coors is undefeated, so this may come back down to Earth, but so far Gomber has handled Coors well. He's also done well overall, so there aren't massively splits with either Elias Diaz or Dom Nunez behind the plate, but I did notice one thing I wanted to explore.

The SwStr% and CSW were different enough in favor of Diaz that I wanted to dig into it. It's entirely possible that, since Diaz has caught more innings with Gomber, his rates are skewed because of that, but I also noticed a difference in the pitch mix.

The first thing that stands out is that Nunez is more four-seamer heavy with two strikes. Considering Gomber gets low SwStr% on his four-seamer, this could be one reason why the swinging strike rates are down with Nunez behind the plate. I thought that Nunez had maybe gone more fastball-heavy because he caught more games in Coors, but Gomber has started five games at home and Diaz has caught four of them, which means Nunez has gone more four-seamer heavy even though he's been catching Gomber on the road.

Diaz has also been spreading out the pitch mix more with two strikes. Nunez is heavy four-seamer and curve, whereas Diaz has also uses the slider and changeup a substantial amount. Considering those pitches have a much higher SwStr% when Diaz is behind the plate, it's possible that he has a better sense of when to marshal those offerings.

Overall, Gomber has been a solid pitcher regardless of who is behind the plate, but I think it's noticeable that Diaz utilizes more of his repertoire, even in Coors, and has been able to get better swing-and-miss performances because of it. Knowing that Diaz caught Gomber's last outing against the Padres makes me even more interested to see how that duo works together throughout the remainder of the year.

Dylan Cease, Chicago White Sox

Dylan Cease is in the middle of a breakout year, so it's weird to see him on a list about something negative, right? Well, this one will be short because it's more about re-establishing a truth than digging for new information. During the Yermin Mercedes breakout and the Yasmani Grandal batting average slump, there was a lot of talk about whether or not Grandal would lose playing time.

In fact, Tony La Russa even started getting Zack Collins more innings behind the plate, but there is still one truth we shouldn't overlook when it comes to Grandal: the man is good for his pitchers.

In addition to the massive split in dERA, we can also see a big jump in SwStr%, Whiff/Sw and CSW. The one reason I want to highlight this, in addition to propping up Grandal, is because there are two major differences in pitch mix that may lead to this split in results.

Grandal has the higher swing-and-miss metrics, but notice how he goes to the four-seamer more with two strikes than the slider. That would seem to be counter-intuitive since the slider is the most GIF-able pitch that Cease throws, but the four-seam has a 14.5% SwStr with Grandal and a 12.6% SwStr with Collins. What's also interesting is that the slider, even though Grandal uses it less with two strikes, has a 24.4% SwStr with him and a 15.6% SwStr with Collins.

Now, I know the sample size in pitches isn't close, so we need to factor that in and not jump to too many conclusions, but I think it's another example that sometimes consistently using your best swing-and-miss pitch when you're ahead in the count isn't always the best strategy. If hitters are expecting it, they're far more likely to hit it, so varying up your sequencing can lead to more swings and misses.

I also want to highlight the jump in curve usage, with Grandal using the curve more and also more with two strikes. Perhaps this could be a good recipe for Cease since the curve has a 37% CSW as a third pitch with Grandal while the changeup has a 20.6% CSW as the third pitch for Collins. This is admittedly the least actionable section of this article, but I think it's interesting with a developing pitcher to see how valuable a veteran catcher can be, especially as the pitcher is learning which pitches to trust or not.

Dylan Bundy, Alex Cobb, Griffin Canning, Andrew Heaney, L.A. Angels

You may notice a similarity between the four names listed above. Honestly, this was not something I came into this article expecting to find, but it seems like the majority of the Angels pitching staff is getting drastically different results based on who is behind the plate. In fact, it seems like one name keeps standing out in the wrong way. Let's look at the numbers.

BUNDY:

COBB:

CANNING: 

HEANEY: 

With the exception of some bad Drew Butera numbers for Andrew Heaney and Dylan Bundy, it's pretty clear from the stats that Angels pitchers are pitching worse when Kurt Suzuki is behind the dish, especially when compared to Max Stassi, who has recently returned from the IL.

If we look specifically at Bundy, who has struggled a lot this year, a few things jump out: his barrel rate with Suzuki behind the plate is similar, but the DHH% is way up when throwing to Suzuki, the groundball rate is down, as are the swing-and-miss metrics (SwStr% and Whiff/Swing). I also notice that Stassi has the highest groundball rate of catchers working with Bundy and also the lowest vertical movement number, which may be correlated.

If we dig deeper into the pitch mix, we can see a couple key differences:

Stassi is slightly more four-seam heavy with two strikes, but he also relies primarily on the four-seam, slider, and changeup, whereas Suzuki uses the curve a decent amount with two-strikes. That pitch has a 9.8% SwStr with Suzuki and has way more success as a called strike pitch, which may be why Bundy's swing-and-miss numbers are slightly better with Stassi.

The changeup has also been a drastically better pitch with Stassi, with a 3.69 dERA and 21.1% SwStr% when he is calling pitches as opposed to a 9.06 dERA and a 13.7% SwStr% when Suzuki is working with Bundy. This could be nothing, but it's important to pay attention to going forward because Stassi's use of the pitch with two-strikes suggests he may have more faith or confidence in the pitch than Suzuki does.

As with all of the examples given above, we're just scratching the surface here. I am not suggesting that the catcher playing is the main reason Bundy has been bad this year, but I know that pitchers are creatures of habit and comfort, and when those things are messed with, a poor performance can follow.

In the end, I think that these splits can point out some meaningful differences in performance and philosophy, even if they are not yet providing hard and fast answers. My suggestion would be to take note of the things that jump out above and then watch for them in previous or subsequent starts.

If a pitcher has a really good or bad performance, take a look at the Player Breakdown on Baseball Savant and see what the pitch mix was, then see who was catching, and see if it tracks with what we're seeing up until that point. By identifying patterns like this, we can begin to make better Start/Sit decisions when we're on the fence about using a pitcher or not. At worst, we simply have one more tool in our tool box, and that's never a bad thing.

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