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Using Sinkers For Called Strikes

There’s more than one way for a pitcher to chase called strikes.

St. Louis Cardinals v Kansas City Royals Photo by Ed Zurga/Getty Images

The other week I discussed one of the ways the St. Louis Cardinals, and specifically Miles Mikolas, are able to get so many called strikes. I looked at how high breaking pitches can be exploited in the upper part of the zone to get early count strikes or help a pitcher come back from behind in the count.

If you haven’t read that piece yet, feel free to go back and read it here.

The Trend - Glove Side Sinkers

Today I want to look at another pitch and location pairing that helps pitchers get a lot of called strikes.

That means I’m going to repeat some of the same ideas that I brought up when I discussed high breaking balls but that’s okay. I’m going to make the argument that the subject for today has been a bigger boon for the Cardinals ability to get called strikes

That’s because we’re looking at sinkers today, and, specifically, glove side sinkers.

We know that the Cardinals throw a lot of sinkers. In fact, they ranked second in the majors in sinker usage last year and that’s not simply a one-year anomaly. As a staff, they’ve been among the heaviest users of sinkers for a little while now.

The downside of the sinker is that it generally isn’t a pitch that misses a lot of bats. We know that. It’s mainly a pitch that manages contact and keeps the ball on the ground. But while the pitch may struggle to get whiffs, it can get called strikes. I already gave away the zone in which these called strikes come so let’s take a step back for a minute and discuss traditional pitching knowledge.

Generally a major idea of pitching is to throw a pitch in the direction of it’s break. So if it breaks glove side, you throw it glove side and if it breaks arm side you throw it arm side.

Think about how sliders are thrown low and outside to right-handed hitters almost exclusively. For a right-handed pitcher that’s the glove side so we have a glove side location on a glove side breaking pitch.

You can think about changeups as doing the same thing in the other direction. Most changeups are also thrown down and away but changeups aren’t generally thrown right-on-right or left-on-left. The down and away spot is usually a pitcher’s arm side so now we’re looking at an arm side breaking pitch being thrown to the arm side.

You can see where this is going. Sinkers, which break to the arm side, are typically thrown to a pitcher’s arm side.

This is generally how pitchers approach pitching because it’s simply easier to command pitches that way and those locations are where they generally perform at their best. So it takes a pitcher with good command to use his pitches differently.

So while I already looked at pitchers who can use their breaking balls in an unorthodox location to get called strikes, today I want to look at pitchers who can use their sinkers in an unorthodox way.

Namely, pitchers who target the glove side with their sinkers.

Much like high curveballs fared better than low curveballs in the aggregate. So too do glove side sinkers fare better than arm side sinkers. For now, that statement only refers to glove side sinkers in the zone vs arm side sinkers in the zone. We’ll get to how they perform out of the zone later in this piece.

This first table is looking at right-handed pitchers only and the next one will look at left-handed pitchers only.

RHP Glove Side Sinkers vs Arm Side Sinkers

Pitch Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Pitch Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Glove Side 0.264 3.5 37.3% 11.3%
Arm Side 0.329 2.5 72.6% 10.8%

LHP Glove Side Sinkers vs Arm Side Sinkers

Pitch Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Pitch Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Glove Side 0.258 3.8 42.2% 10.7%
Arm Side 0.328 2.8 70.6% 13.5%

There’s not a whole lot of gray area here. Glove side sinkers simply perform better in the zone than arm side sinkers. The difference is that arm side sinkers are thrown more. Like a lot more. Pitchers put arm side sinkers in the zone 22,743 times in 2023 and only put glove side sinkers in the zone 15,133 times.

Glove side sinkers are uncommon and that is likely a major key to their success. You can deduce that from the significantly lower swing rate. When a hitter is taking a pitch in the zone, that’s a win for the pitcher.

Now on the flip side, glove side sinkers have the same risk that high breaking balls do. If a pitcher misses the zone, the pitch fares significantly worse.

Here are the results for right-handed pitchers when they miss the zone to the glove side vs the arm side:

RHP Glove Side Sinkers vs Arm Side Sinkers - OOZ

Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Glove Side (OOZ) 0.454 -4.2 8.7% 25.0%
Arm Side (OOZ) 0.371 -1.9 35.2% 23.1%

Lefties fare similarly poorly when they miss to their glove side:

LHP Glove Side Sinkers vs Arm Side Sinkers - OOZ

Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Glove Side (OOZ) 0.424 -4.4 11.6% 26.1%
Arm Side (OOZ) 0.366 -1.9 31.8% 27.8%

It’s clear where the struggles come from. Hitters simply don’t chase glove side sinkers out of the zone. If a pitcher misses to his glove side it’s pretty much a guaranteed ball.

So to use this strategy effectively, we need to put a premium on command. This is the same conclusion that we came to with high curveballs. Heavy glove side sinker usage is a viable strategy for pitchers who are able to effectively command their sinkers to both sides of the plate. If a pitcher doesn’t have good command, he’s likely to hurt himself more than he helps himself by missing the zone and giving hitters balls that they aren’t going to chase.

So far this argument hasn’t really diverged from the argument we made when it came to high breaking balls. That’s about to change.

When we looked at high breaking balls, we saw that hitters tend to lay off them until they get two strikes but that’s when they start swinging heavily and that negated the pitcher’s advantage

So, we should expect to see the same thing with glove side sinkers, right? Well...not exactly.

RHP Sinkers with 2 Strikes by Location

Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Glove Side 0.184 4.9 60.80% 10.70%
Arm Side 0.276 0.2 94.70% 10.10%

LHP Sinkers with 2 Strikes by Location

Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Location wOBA Pitcher Run Value/100 Swing Rate Whiff Rate
Glove Side 0.169 5.6 64.9% 9.0%
Arm Side 0.234 1.9 94.7% 14.5%

So this is interesting. Hitters do swing more against glove side sinkers when there are 2 strikes but they swing nearly every time there’s an in zone sinker thrown to the arm side in such situations. Even more shocking is that in zone glove side sinkers aren’t just the better 2 strike option; it’s not even close.

This is different. This isn’t what we saw when we looked at high curveballs.

I think what I love the most is that teams and pitchers already know this is the case. Do you know how I know? It’s because when hitters have 2 strikes, pitchers actually throw more glove side sinkers than they do arm side sinkers.

Pretty crazy, right?

So this forces us to alter our conclusions. Coming into this piece, I thought I was going to make the have the same conclusion as I did about high breaking balls with 2 strikes but that clearly doesn’t hold. Instead, our conclusion is that pitchers should be throwing glove side sinkers with 2 strikes.

It’s an effective way of getting called punchouts and even when hitters swing, they tend not to do damage. That’s probably why over a quarter (26.7%) of all glove side sinkers were thrown with 2 strikes.

I want to point out here that I was only considering in-zone sinkers in the above tables but I promise that doesn’t skew the results unnaturally. Even when we factor in out of zone pitches, glove side sinkers outperform arm side sinkers by a large margin with 2 strikes.

This is the kind of pitch, location, and count pairing that sinkerballers should be looking to exploit.

So what is causing this trend? It’s hard to say. Perhaps the glove side sinker is simply a better pitch than the arm side sinker. Perhaps there’s an unexpectedness to it. Perhaps it’s becuase hitters are expecting to see a glove side breaking ball so they’re surprised when they see a glove side pitch break in the opposite direction.

There’s a lot of theories we can come up with here but finding an answer is going to require a lot more research and another article if I eventually decide to revisit this topic.

The Cardinals

So which Cardinal do you think uses glove side sinkers the most? If your guess is Miles Mikolas then I applaud you...but you’re wrong.

Mikolas was my guess too and he’s in third place but there’s one pitcher above him who threw over 150 more glove side sinkers in 2023.

Steven Matz.

Cardinals Glove Side Sinker Leaders

Name Pitches wOBA Pitcher Run Value/100
Name Pitches wOBA Pitcher Run Value/100
Matz, Steven LHP 438 0.337 -0.4
Montgomery, Jordan LHP 322 0.279 -0.7
Mikolas, Miles RHP 280 0.298 0.4
Hicks, Jordan RHP 239 0.423 -1.2
Wainwright, Adam RHP 221 0.457 -4.1
Woodford, Jake RHP 192 0.269 0.9
Hudson, Dakota RHP 123 0.304 0.7
Liberatore, Matthew LHP 50 0.232 2.6

Note that these results include pitches inside and outside the zone. That’s a necessary caveat because the pitches outside the zone weigh down the results. Still, though, only Adam Wainwright and Jordan Hicks really struggled when they went glove side, though Matz didn’t exactly crush it either.

And there seems to be a pretty clear reason why - they missed the zone too much. Jordan Hicks threw 54% of his glove side sinkers outside the zone, Wainwright missed with 55% of his glove sinkers and Matz was at a whopping 58%.

Remember, these aren’t pitches that get chased very often so missing the zone is almost a guaranteed ball.

On the flip side we have guys like Miles Mikolas, Jake Woodford, and Matthew Liberatore who were all in the zone at greater than a 50% clip with their glove side sinkers.

Command matters. This strategy works if a pitcher can hit his spot and keep the ball in the zone.

But let’s push past that for now.

The fact that Steven Matz is so far ahead of anyone else on the staff is especially notable because he threw more glove side sinkers than all but 4 major league pitchers in 2023 (the only 4 pitchers who threw more than him were Brady Singer, Logan Webb, Drew Smyly, and Alex Cobb).

A whopping 42% of Matz’s sinkers were thrown to the glove side last year so this strategy is crucial to Steven Matz’s success. That’s not just something that he does occasionally, it’s something he does with nearly every other sinker that he throws.

He actually throws more glove side sinkers than he does arm side sinkers.

I would argue that this is a large reason why Matz tends to not work deep into games (his 17.77 pitches per inning pitched is very high for a starting pitcher). He throws a lot of glove side sinkers but he doesn’t have the command to keep them in the zone. That leads to a lot of balls and when he does put them in the zone, it generally leads to takes, not quick outs.

So while I love the idea of a glove side sinker for pitchers who can command their sinker to both sides of the plate, Steven Matz might actually be throwing too many glove side sinkers.

Steven Matz Glove Side Sinkers vs Arm Side Sinkers

Location wOBA Pitcher Run Value/100 Swing Rate Chase Rate Whiff Rate
Location wOBA Pitcher Run Value/100 Swing Rate Chase Rate Whiff Rate
Glove Side 0.337 -0.4 32.2% 16.1% 19.1%
Arm Side 0.250 1.3 46.4% 16.8% 35.1%

There’s two ways to look at his. The first is by considering that the primary value of glove side sinkers is to get called strikes. That happens in part because they’re unexpected. Matz may actually somewhat neutralizing the pitch’s ability to get called strikes because the pitch is no longer unexpected; it’s part of the scouting report against him.

The average swing rate against glove side sinkers (including out of the zone sinkers) is 25.9%. That’s well below the swing rate against Matz’s glove side sinkers. So Matz may actually be better off using his arm side sinker more to get whiffs and swings while lowering the usage of his glove side sinkers a bit in an effort to get a higher rate of called strikes.

So that’s option 1 for Matz - decreased usage. Option number 2 is better command. If he can command the pitch better then he can likely see better results with the same usage. He’ll get more called strikes and probably keep his pitch count down a bit better.

Option 1 is likely the better option because, frankly, it’s easy to bank on decreased usage than it is to bank on improved command for a 32-year-old pitcher.

Final Thoughts

I love glove side sinkers. I love high breaking balls. They’re weird and interesting and come with a ton of nuance that leads to further investigation and a better understanding of the game we all love. This is the kind of stuff that makes me nerd out about baseball which makes me...well...a nerd probably. But I hope you found this discussion fruitful. I learned a lot from writing both this article and the breaking ball article.

Thank you to everyone who successfully waded through an ocean of tables and numbers with me to get to the end of this piece. I hope you enjoyed it.

Have a great Tuesday.