Does Pitch Arsenal Really Matter?

In my research over the last couple of months, I have been paying close attention to the pitch mix of each pitcher I study. This means I want to know how many different pitches they can throw and how they distribute those different offerings.

It seemed logical to me that pitchers with more pitches in their repertoire would be better pitchers, and pitchers with fewer would be worse. The other day I realized that I had never actually put that theory to the test, so I was really making a lot of assumptions. So I put it to the test to see what I would find.

I set a 15% requirement here. That means that a pitcher that has four pitches he throws more than 15% of the time will fall into the "four-pitch" category. A pitcher with three pitches over 1% usage goes into the "three-pitch" category, and pitchers with just two offerings over 15% go into the "two-pitch" category. Then I went ahead and took those groupings together and looked at their collective results.

Trial 1

Four Pitches

Using pitchers that made at least three starts last year, here is the full list of pitchers that threw four different pitches at 15% or more frequency:

Brett Anderson, Cal Quantrill, Carlos Martinez, Casey Mize, David Peterson, Gio Gonzalez, Jeff Samardzija, Jesus Luzardo, Johnny Cueto, Jordan Montgomery, Justus Sheffield, Luis Castillo, Marco Gonzales, Martin Perez, Matt Shoemaker, Mike Fiers, Pablo Lopez, Robbie Erlin, Ryan Castellani, Sixto Sanchez, Sonny Gray, Touki Toussaint, Trevor Cahill, Zac Gallen

Here are the stats this collective group of pitchers has put up:

Pretty league average-ish numbers there.

Three Pitches

This is the biggest list, 114 different pitchers fall into this category. Because of that, I will skip listing names and just show the results.

Two Pitches

This is also a pretty sizeable list of 61 pitchers. It includes guys like Framber Valdez, Mike Clevinger, Joe Musgrove, Brady Singer, Julio Urias, Max Fried, Tyler Glasnow, and Lucas Giolito.

So all together, these groupings of pitchers all look pretty similar. They have nearly identical CSW (called strike + whiff) rates and everything else is also very close. The one that stands out a bit is the four-pitch group being behind in swinging-strike rate. That could be the result of some randomness in how I did this, but I think it could also be a result of some selection bias.

By that I mean, pitchers that only throw or three pitches but have stuck around in the big leagues probably have one or two really good pitches that are good enough to rely on. When you start looking at guys with four or five pitches, that might be a sign that they don't have any dominant pitches and need to survive by just keeping hitters off balance. It makes sense that that could manifest in a lower whiff and strikeout rate, while everything else stays similar - which is what we see here.

Trial 2

If we raise the threshold to 25% (meaning now the pitchers in the three-pitch group will be pitchers that have thrown three different pitches over 25% usage) and run it again, here's what we see.

The four-pitch group goes away since nobody threw four pitches exactly 25% of the time. The three-pitch group is restricted to only Brad Keller, Chris Mazza, Gio Gonzalez, Jorge Lopez, Jose Berrios, Masahiro Tanaka, Ryan Yarbrough, Sonny Gray, Tanner Houck, Tyler Anderson, and Wade LeBlanc. The two-pitch and one-pitch groups are about the same size. Here's are how these groups have performed.

Three-Pitch Group

Two-Pitch Group

One-Pitch Group

If you just look at the 2018-2020 rows, the three-pitch group does appear to be the worst. This is pretty much completely opposite of what I expected to find.

Does High Velocity Make For a Better Pitcher?

I went ahead and did the same exercise, this time just grouping pitchers by their fastball velocity. I made four groupings based on the average velocity of every four-seamer and sinker thrown by each pitcher. Here's how I made the groups:

Group 1: Velo above 96
Group 2: Velo 93-96
Group 3: Velo 91-93
Group 4: Velo below 91

And here are the results.

Group 1 (high velo)

Group 2 (medium-high velo)

Group 3 (medium-low velo)

Group 4 (low velo)

The super high-velocity pitchers (guys like Yu Darvish, Dinelson Lamet, Jacob deGrom, Gerrit Cole, Tyler Glasnow) clearly stand above the rest. There are huge differences between that grouping and the rest. However, you can tell that the 93-95 mile per hour pitchers aren't significantly better than the slowest velocity pitchers. They get more strikeouts, yes, but the ERA and WHIP measures are right around the same.

Conclusion

Honestly, my thought when I started this was that I would prove that it's better to have a diverse pitch arsenal and then point out to all of you a list of names of guys that have it. Since this study proved me wrong, I can't do that anymore.

What I will say is that, hey, you shouldn't really care how many pitches a guy throws when evaluating them, because the number of pitches in your pitch arsenal does not seem to correlate with success. Having a heavy fastball sure does though, so you can bump up any pitchers entering the league that are hitting 97+ on the gun.

So that was a bit anti-climactic, but hopefully this will dispel any previously held myths that more pitches means more success.

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