Largely Theoretical Pitcher Arsenal Construction

FP, SiP, and SoP: Specific names for pitches probably matter a lot less than we think

I’ve been thinking about this fantastic article about pitch classification. I think about it maybe once or twice a day, but a little bit more recently because I’ve been thinking about how pitchers can be the best versions of themselves.

I think it starts with the body’s natural inclination towards being able to handle the volume of a larger workload like starters and bulk pitchers, or being better suited for shorter outings like relief pitchers.

For larger volume pitchers, they typically need three distinct pitch shapes to be able to effectively navigate a batting order at least two times. Most arsenals look like this:

• Highest speed, low/medium movement pitch (the fast pitch - FP)

• Lower speed, low/medium movement pitch (the secondary in-zone pitch - SiP)

• Lower speed, medium/high movement pitch (the secondary out-of-zone pitch - SoP)

A few things to note here: Smaller volume pitchers can typically survive with just two of those types of pitches. Also, both speed and movement are relative to the individual and the rest of their arsenal. High speed fastballs tend to allow for more wiggle room and “arsenal protection” regardless of shape, but velocity isn’t everything.

Pitches with a lower amount of movement are easier to command, so those tend to be higher usage pitches because throwing in the zone is much more valuable than throwing outside of the zone. However, its lack of movement tends to make it easier for hitters to make contact with.

FPs that are platoon neutral tend to be more successful for high volume pitchers. This is their primary in-zone pitch that they can command well to hitters on both sides of the plate. It is best used to generate called strikes and foul balls, and to generate less than ideal contact if the ball is put in play.

An FP with more velocity allows a pitcher to be less fine with their command because it is usually difficult to get an ideal swing on a pitch like that. This also “protects” the other pitches they throw; if a hitter has to be ready for high velocity, they’re less likely to sit on the SiP or SoP.

The ideal FP shape depends on the pitcher and what the rest of their arsenal looks like. I think it is best to lean into the strengths of an athlete rather than trying to make their bodies do something they’re uncomfortable with, and a pitcher could have multiple FP shapes. Some pitchers have an inclination to throw a cutting or rising FP (gFP: glove-side moving FP) — these tend to be platoon neutral or even better against opposite handed batters. Running or sinking FPs (aFP: arm-side moving FP) tend to be better against same handed batters.

SiPs would be a little less easier to command than an FP, but still able to get a strike when needed. They also might get more swing and miss than FPs. Glove-side moving SiPs (gSiP) work best against same handed batters while arm-side moving SiPs (aSiP) work best against opposite handed batters. Again, there is no ideal shape here and a pitcher could have more than one SiP shape.

SoPs are the most difficult to command, but tend to get the most swing and miss. They are often difficult to get a good swing on due to their movement and usually don’t end up in the zone. There is no one ideal shape other than the one that works best for the individual. Glove-side moving SoPs (gSoP) work best against same handed batters while arm-side moving SoPs (aSoP) work best against opposite handed batters. However, gSoPs can still be highly effective versus opposite handed batters and aSoPs versus same handed batters when their primary movement pattern involves more sink than run or sweep.

Constructing an Arsenal

The athlete should always lean into what they do best. Their best pitch is the one that should be built around. It helps if their best pitch has “outlier” traits different from what other pitchers do with similar pitches — comparing FPs with FPs, SiPs with SiPs, and SoPs with SoPs.

There’s no one way to build an arsenal, but for larger volume pitchers, having an FP and at least one SiP that move in opposite directions of each other is important. Without at least one platoon-neutral in-zone pitch, a pitcher would almost certainly struggle in a large volume role where they would be tasked with getting opposite handed batters out with relatively high frequency. Same side moving FPs and SiPs look more like the set-up of a low volume relief pitcher because they would have a clear weakness.

When an SoP is a pitcher’s best offering, it presents a tricky situation because the goal would be to create as many situations as possible to throw the SoP. This is where the primary function of a SiP would be to bridge the gap between the FP and SoP. An aSiP would pair best with an aSoP, and a gSiP with a gSoP. The ideal FP shape in the case of an aSoP/aSiP arsenal would be a gFP to help neutralize while an aFP would be best for a gSoP/gSiP set-up.

The main take away here is that the athletes strengths should build around their best pitch to the best of their abilities. Now, we’ll take a look at some real examples of this new way to classify pitches…

Jared Jones

Let’s start with one of the hottest names in baseball right now:

Jones’s arsenal consists of:

• An aFP - high velo with good rise

• A gSiP - his best pitch, tight late break with gyro movement which helps it play well versus both RHB and LHB (this is his outlier pitch)

• An aSiP - his offspeed pitch primarily used against opposite handed batters, not that great of an in-zone offering, but his gSiP helps fill that void in-zone

• A gSoP - more of a sink/drop profile, making it acceptable against both sides of the plate; shape tunnels well with gSiP, so he’s able to accentuate his best pitch even more

His aFP offers plenty of protection for his gSiP due to it’s velocity. Jones is an excellent example of someone who constructed their arsenal based on their strengths and built around their best pitch.

Adam Oller

Here we have Adam Oller’s pitch shapes from 2022. I wanted to choose a good example of poor arsenal construction because we have a bit of survivorship bias in the major leagues. The vast majority of the guys who make it to the major leagues are good at what they do. Thankfully these are old shapes and Oller made some good adjustments in 2023 (more on that later), so I don’t feel as bad critiquing him here.

The first thing you’ll notice is a lack of distinct shapes. This is typically a sign of an ineffective pitcher, especially when it happens unintentionally. The main action that needs to be taken when this is the case is the pitcher needs to clean-up their arsenal and throw more distinct shapes — which he did in 2023:

There still isn’t enough optimal separation between his FP and SiPs, but we at least have something we can work with here and analyze:

• An aFP - running, but not much rise or sink, good enough velo at 93mph

• An aSiP - shape is inconsistent in a similar way to Jones, mostly a “show” pitch for opposite handed batters

• A gSiP - tight, consistent shape, good strike pitch to bridge the gap to his best pitch from his aFP

• A gSiP - sweeping and sinking movement, by far his best pitch, not too platoon neutral due to its sweep

While Oller did take actionable steps in the right direction, there are still a few more things I’d have him do. Step one would be to adjust his aFP to add more run; it looks like his body’s natural inclination is to throw more of a running, sinking aFP than a rising one, so it would be important to play into that. This would allow for more of a movement gap between his aFP and the gSiP he has a good feel for. It helps that he flashed an aFP shape with more run and sink in 2022. The gSiP serves it’s purpose as a bridge to the gSoP so I wouldn’t change anything else there. Lastly, I’d scrap the aSiP; it would be a bit redundant with the emergence of a stronger aFP shape.

Edwin Diaz

I wanted to throw in a quality lower volume relief pitcher here, so look no further than one of the most dominant arms in the game.

Diaz’s arsenal consists of:

• An aFP - his best pitch, strong running movement and high velo

• A gSiP - very minimal cut/break, so it plays more platoon neutral than most gSiPs, able to land it for a strike

Diaz is effective with two pitches because he rarely faces more than a handful of batters in each appearance. It’s a simple yet effective arsenal that works well for the athlete’s body and his role. Here’s one more short volume example that I’d consider the inverse of Diaz…

Calvin Faucher

Faucher’s arsenal from 2022-2023 was less than ideal. Here we have a blending of gSiPs that spill into his gSoP. The gSoP is his best pitch; it’s a late breaking and steep hammer with relatively high velo. Faucher struggled to get to his gSoP due to a lack of a clear bridge gSiP that he could also land for strikes. He started to make the adjustment in 2023, but went all the way in 2024 and the results so far have been excellent (although is has been in a small sample). Here’s his new arsenal:

• An aFP - a rising and running offering with good velocity, plays well against opposite handed batters

• A gSiP - mainly a bridge pitch, but can be thrown in-zone enough and plays well against same handed batters

• His stellar gSoP - his best pitch the more drop/sink profile allows it to play a bit more platoon neutral than other gSoPs

Faucher didn’t start throwing his newest gSiP shape at a meaningful amount until 4/15/2023. His FIP in 27.2 ML innings from his debut until 4/14/2023 was 5.59. Since he started throwing that relatively new gSiP, his FIP has been 3.36 in 28 IP. Both samples are relatively small in the grand scheme of things, but the trends and improvements are significant and worth keeping an eye on going forward.

Conclusion

Something that would be worth writing about but impossible to quantify in a meaningful way would be pitch usage and sequencing. Even though they’re largely random, they also play a role here, but again it comes down to the individual athlete and what they’re most comfortable with. I like the idea of simple and fewer labels when it comes to forms of art. Talented artists don’t really need more coaching and more labels, they need guidance occasionally and feedback to help them be the best versions of themselves. However, the most important thing might be for us to get out of the way and let them be artists.

*All graphs courtesy of Baseball Savant