Does Taijuan Walker have a fastball problem?

Taijuan Walker might have a fastball problem. Perhaps “problem” is too strong of a word. A predicament? A quandary? At the very least, he’s managed to confuse yours truly.

Walker threw 31 heaters on Sunday as he struck out 10 Los Angeles Angels. He was able to command it consistently at the top of the zone and earned a called strike or whiff a dozen times over his six innings of work. It’s the best his fastball has looked all season, and, not-so-coincidentally, the hardest, too.

Heading into his next start, Walker may be inclined to continue his season-long quest to elevate his fastball. I’m not so sure it’s the right call.

What is Taijuan Walker trying to do with his fastball?

Major League Baseball has fully entrenched itself in the era of the high four-seam fastball, Walker included. 

Walker’s game plan on Sunday, as it’s been for much of the season, was to litter the letters with strikes. It’s helped him earn early strikes and set up the secondaries that are crucial to his game; namely, his splitter. However, he’s not generating as many whiffs (20.5%) as the guys that throw as many high fastballs as him, such as Dylan Cease or Michael Kopech.

The art of throwing up in the zone is more than just location. Velocity and spin are important, too, and among other factors, help optimize one’s Vertical Approach Angle (VAA). This determines how “flat” a pitch is. Regarding fastballs, flatter is better due to the rising illusion it facilitates. Furthermore, VAA is best utilized when adjusted for pitch height, contextualizing the metric (Vertical Approach Angle Above Average, VA AA).

Essentially, good high fastballs work because hitters are swinging under them. They swing under them because they perceive the pitch to be lower than it actually is. 

At this point, we’ve established two things. One, Taijuan Walker really likes the high fastball. Two, he probably shouldn’t.

How concerned should we be?

So far, the 2022 season has been pretty kind to Walker. He’s pitched to a 3.08 ERA and his peripherals don’t suggest significant regression. Since returning from injury, he has gone five or more innings in eight of nine starts. 

What bothers me is the vulnerable state of his heater and a waning ability to generate strikeouts. 

Fastballs up in the zone are nice when they garner swings and misses, but they come with the built-in launch angle risk. If guys aren’t swinging and missing the barrels are bound to come eventually. Out of pure caution, it may be worthwhile to lower some of those four-seamers. 

As Mike Petriello pointed out, Walker’s seen a rather sharp decline in strikeouts recently. A lack of a quality fastball has dampened his ability to put guys away, and it shows. Likewise, he’s getting virtually zero production from his breaking pitches. 

Walker has featured a slider about 20% of the time during his two-year tenure as a New York Met. Last year, its 24.4% CSW% ranked 177th in the bigs. A year later and that mark has dropped to 22.1%. In 2022, it’s been barreled up twice as often as the league average and is garnering whiffs at an incredibly poor 8.4% clip.

Additionally, there is not a remarkable curveball to fall back on. It’s used almost entirely as a “get me over” pitch early in counts. While successful (35.5% CSW%), he is yet to record a strikeout with it in 2022.

Is Walker’s splitter a saving grace?

Subsequently, Walker relies on a splitter he’s throwing 30% of the time. To his credit, it’s been phenomenal. The only two pitchers with more negative run value on splitters this year are Tony Gonsolin and Kevin Gausman, a testament to Walker’s early effectiveness. 

Yet, I find myself hesitant to buy-in. Splitters are notoriously inconsistent, even for guys that truly feature their splitter (hi, Chasen Shreve). Walker has already had four starts this year with a swinging strike rate below 12% on his splitter. Gausman is yet to have one. Gonsolin has four but has two great breaking pitches to lean on.

Thus, we have a pitcher with an uninspiring fastball, a strong splitter, and no other out pitch. The dark clouds of a tough summer schedule are rolling in, and such a repertoire may not weather the storm.

Walker’s peculiar pitch mix decisions

Perhaps the most confusing aspect of Walker’s season is his choice to abandon his sinker. Now thrown a mere 6% of the time, Walker’s increased splitter usage came at a direct cost to his best pitch from 2021. 

Walker’s breakers likely pushed him towards this decision. If he could not count on them to generate whiffs, he had to double down on his splitter. But to break up with it for a fastball that I’ve spent 800 words criticizing? By CSW%, it was the 24th best sinker in baseball! He commanded it really well! At its best, it was the out pitch he needed! 

Yes, Walker’s sinker hasn’t performed as well this year in its small sample size. Still, it should see more usage than it is right now. Preferably, replacing some fastballs and sliders. There isn’t much from a spin direction standpoint to suggest it tunnels with his splitter any worse, especially to right-handed hitters. 

Filling up the inside and outside borders of the plate with sinkers feels like an easy way to mitigate some concerns. Allowing Walker to throw fewer fastballs and sliders might be the “do more good things, do less bad things” approach that rights the ship before the waters get too rocky. At the very least, we’d get the aesthetic value of a front-door sinker.

Does Taijuan Walker have a fastball problem? Probably. But it’s the choices that surround the pitch that will define his season.

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