Pitch plots are like a Rorschach inkblot test—look at them without context and you’ll end up seeing whatever you want. That doesn’t mean it’s real, though. There’s a lot to unpack after a start, and it doesn’t do any justice to throw it all onto a single image and try to parse that. Instead, we’re going to try something else: painting with a finer brush. This is an experiment to see what we can do when we break down and rebuild a strike zone. It’s a journey that I’m sure will be defined by the friends we make along the way. For the inaugural piece, let’s get simple and look at two starts: one good and one bad.
Quick Note: The plots you see below are all built from the catcher’s perspective. That means right-handed batters will be on the left and vice versa. Cool? Cool.
The Good
Take a look at this clip.
I’ve watched this over 100 times, easily. This stupid flailing inflatable dinosaur is etched into my brain at this point, and I still watch this clip once a week. It never matters how many times I see it, because it’s always going to be absolutely delightful. I feel the same way about Blake Snell’s curveball. I really really love Snell’s curveball. The worst thing about Blake Snell is that Baseball Reference says his nickname is Snellzilla, and that’s his Twitter handle too. Sure, I guess he’s 6’4″, but it feels like we could be calling his curveball “Snell Mail” or something and it would work a whole lot better. On April 8th, Snell racked up 11 strikeouts in 6 innings of work, and 7 of those came from his curveball (Snell Mail). Here’s every curve he threw that day, at an average velocity of 81.0 mph.
This is, for the most part, excellent execution. And it leads to great whiffs like this one against Jose Abreu that made our Nastiest Pitch list.
There was also a curve that didn’t drop quite enough, and Jose Rondon took it yard to tag Snell with his only earned run of the start.
Back to the praise—he complimented his curveball with an even more excellent execution of his fastball, scattering it vertically but overall pounding the zone at an average velocity of 95.7 mph, hitting 97.2 mph at the peak.
Then, mix in a changeup down and away from righties at a whole 9mph slower, 86.6mph….
… and four sliders that come in on those same righties between 86 mph and 89 mph. 
And you’ve got something that looks like this:
Look at how well-focused each of these pitch types ends up being. There’s some hits scattered throughout but what’s so impressive is the execution of location each pitch right where they should go. Sure, it makes sense—fastballs high, curves low, changeups down and away where batters can’t get to them. It’s so easy that… wait, right, almost nobody can do it, and anybody that can do it plays in the majors.
Snell’s pitch mix is consistently made up of his two most dominant pitches. In this start, he threw 42 fastballs and 36 curveballs out of 100 total pitches. Last year, he threw his four-seamer 51.5% of the time and his curveball 20.2% of the time. Yet, he ended up throwing his curve for 93 strikeouts last year, leaving his fastball in second place with 77 strikeouts. The curveball saw less than half of the usage of his fastball, but ended up accounting for more walks back to the dugout, because it’s really good.
Really, really, inflatable-dinosaur-falling-on-a- basketball-court good.
Through three starts this year, Snell’s throwing the fastball only 39.5% and his curve is up to a 33% usage rate. We’ll see if it evens out or if he’s making an effort to work the curve into the mix more often. Being able to move between 95 mph and 80 mph with movement and precision means he can work a batter vertically and not have to worry about jamming him horizontally. Snell is a smart pitcher: he doesn’t extend on the left or right of the zone. He’s not going to let a player crush a fastball inside—they’re going to have to work high or low instead, a harder prospect than turning on a heater and barreling it. Even when his curve got touched up, it was right there on the margin at the knees.
The Bad
I just want to be clear that there are a lot of bad starts in the MLB. This isn’t that. The starts we’re going to try to focus on, moving forward, are the weird ones. Times where something’s not working or some bad choices get made. Everyone runs into a couple of hot bats, and we just don’t have enough ink to cover every time Trevor Rosenthal takes the mound (sorry).
So that brings us to a man who Baseball Reference tells me is nicknamed “Wheels.” Zack Wheeler experienced a second-half breakout last year, posting a 1.18 ERA over the last 11 starts of the season after posting a 4.44 ERA through the first 18 starts. Dig into that a little bit and you’ll notice his strikeout rate remained just about unchanged—an 8.9 SO/9 in the first half and 8.8 SO/9 in the second half.
Anyway, on April 7th he walked 7 batters and gave up 7 runs. That’s not great if you’re trying to keep a breakout going.
So what was going wrong, exactly? Well to start, his slider was doing something counter-intuitive, in that it was not actually sliding very well.
He’s got a few working down and away from righties but then he’s also hanging a ton of them well into the zone, and he’s even got a cluster of them way up there on the left. One of those dots, the one further to the left in that upper cluster, is a great example. On a 3-2 count in the 5th inning, Wheeler throws a 91.4 mph slider to Howie Kendrick that goes up and in. If you look at this pitch and don’t quite see a slider, I won’t blame you. It’s barely got the look.
With the slider not working, Wheeler was doomed by an inaccurate fastball.
Last year, Wheeler notched 72 strikeouts with his fastball, while his second most effective pitches were his curve and slider, for 32 and 30 strikeouts respectively. In other words, he needs to set the table with the fastball if he’s looking for a good start. Instead, it ended up being the pitch responsible for 4 of his 7 walks. The best example comes later in the 5th inning. After walking Kendrick with that aforementioned slider, Wheeler throws a down and in 96.6 mph fastball to Anthony Rendon for ball four and puts runners on 1st and 2nd. Then, a flyout moves Kendrick to 3rd, and in the next at-bat, a mid-level slider on the outside walks Ryan Zimmerman to load the bases, and we get to the final doomed at-bat of Wheeler’s day.
In a 3-1 count with the bases loaded, where Wheeler would desperately like to throw a strike, he goes to his fastball one more time. Even though it hadn’t been working for him so far, he tried to put a 96.2 mph fastball up and in to hopefully jam Kurt Suzuki. Instead, he walks Suzuki, brings home Kendrick, and gets pulled. Tough break.
On top of all that, Wheeler barely threw his curve—his second most successful strikeout pitch from last year—even though he was getting decent location on it.
Was it possible this is because he very rarely was in a position to record a strikeout during this start? Except he worked a two-strike count a total of 21 times over the course of 12 at-bats. Not once over those 21 pitches did he throw a single curve. His splitter was working just fine as well.
However, he elected to use the splitter on a two-strike count in three at-bats, with all three of them resulting in a ground out. Last year, Wheeler only used the sinker 15.2% of the time, a percentage he has upped this year to 28.8 so far. We’ll see if that holds, but that new pitch profile coupled with an inaccurate fastball and a slider that is defying its own definition can only take Wheeler so far. In fact, it takes him to this.
When your best pitches aren’t working and you can’t execute, you’re going to end up with this very pretty but ineffective strike zone plot, one that looks a whole lot like this clip feels.
See? Never gets old.
(Photo by Juan DeLeon/Icon Sportswire)