The Most Improved Pitches by PLV (so far)

Pitchers that have potentially added something new in 2023.

Can I share something, just between us?

I am terrible at understanding pitches. I don’t know how pitchers do it! I play Savant’s “guess the pitch” game, and I’m pretty good at four-seamers and curves, and sometimes sliders and changes, but cutters and sinkers vex me. Any I get right are dumb luck.

I think it’s that bewilderment that also allows me to appreciate the intricacies of pitching from the people who do it so well, though.

It’s exciting when pitchers add a new pitch; how it interacts with their other offerings, its ability to fool a batter into thinking it’s something else entirely, and placing a new thought into the hitter’s head. With PLV, we can go a step further. What are hurlers doing to make their existing pitches better?

If you haven’t read about it, you can learn about PLV here. Essentially though, it’s a way to measure a pitch’s effectiveness based on stuff (like speed and movement), location, and category (like batter handedness or count). PLV doesn’t really start to become predictive until 500 pitches, and none of the pitchers we’re discussing today have hit that mark. These pitchers may or may not be making mechanical or substantive changes, but we’ll explore some early changes in pitch PLV to see if we can learn anything new about them.


Logan Webb, San Francisco Giants – Changeup

No changeup thrown more than 200 times in 2023 has improved more by PLV than Webb’s cambio. Webb’s changeup was already good prior to this season – league average for PLV is 5, and Webb’s was at 5.27. This year’s 5.56 mark would have been the 10th best changeup in the entire league in 2022. (For reference, Devin Williams‘ was 5th-best at 5.71 PLV.)

Webb is striking out a career-high 27% of batters he’s facing, and walking a career-low 3.9%. That success is almost entirely attributable so far to that new and improved change. Hitters are whiffing on that offering a whopping 34% of the time (up from 26% last season), even as the whiffs on Webb’s sinker and slider have decreased.

What’s different about Webb’s changeup?

He’s getting way more movement on it, somehow. Webb has always had an elite amount of vertical drop on the pitch, but not much in the way of horizontal movement. After a slight dip in his vertical movement on the changeup last year, that movement is back to elite and while also getting two and a half inches more of horizontal break.

Webb’s change still isn’t elite by horizontal break, but getting more movement on a pitch that already was among the best in vertical break has paid dividends so far.


Yusei Kikuchi, Toronto Blue Jays – Four Seam Fastball

Forget the pitch type for a second, there’s no pitch in baseball that has seen as marked of an improvement by PLV in the past year than Yusei Kikuchi’s four-seamer.

It’s hard to say exactly why it’s been so much more effective, from below-average (4.9 PLV) to above (5.6 PLV). Kikuchi’s four-seamer velocity is up by less than half a mile per hour on average, but unlike Webb’s changeup, it’s moving less and generating fewer whiffs than last season.

Instead, it seems as though Kikuchi is being more judicious with his four-seamer. It got crushed last year to the tune of of a .562 xSLG. Kikuchi is now throwing the four-seamer less, and at least appears to be making more of a concerted effort to get it up in the zone:

2022 Four-Seam Fastballs

2023 Four-Seam Fastballs

It seems to be largely working– Kikuchi has his lowest ERA and xERA of the past three seasons. Interestingly, it doesn’t seem to be a change in “stuff” as much, as was the case with Logan Webb’s changeup, but rather the location of where Kikuchi is throwing his four-seamer. It’s neat that there are different ways for pitchers to improve!


Roansy Contreras, Pittsburgh Pirates – Slider

The 23-year-old Contreras is going on my “a step away from putting it all together” watch list. Contreras hasn’t been great this season (4.79 xERA, almost identical to his actual 4.74), but the slider has taken a jump by PLV. It’s another pitch that has gone from below-average to above in the past year.

Like Logan Webb’s changeup, Contreras’ slider has always had a good amount of vertical drop (40 inches last year), but he’s eliminated its horizontal break weakness, adding nearly 2.5 inches of horizontal break while mostly maintaining that north-south movement.

It’s a good pitch, and Contreras has responded by throwing it more and more each season, now up to 46% of his pitches thrown. The slider gets 37% whiffs, which is pretty good, but is down from last year’s 42%. How is that happening, given that the pitch has increased its movement? Well, about that…

Roansy Contreras Four-Seam Fastballs
Contreras went from throwing an above-average slider with an average four-seamer in 2022 to an elite slider with one of the worst four-seamers in the league in the early going of 2023.

The four-seamer velocity drop is obviously concerning, but Contreras’ run value on the slider tops the major league leaderboard at the moment.

Contreras has done both before – just not at the same time. If he makes a similar jump in his PLV on the four seamer for next year’s version of this article, the Pirates could be looking at one of the best relievers in baseball.

Photo by David J. Griffin/Icon Sportswire
Adapted by Kurt Wasemiller (@KUWasemiller on Twitter / @kurt_player02 on Instagram)

Sean Roberts

Sean Roberts is a baseball columnist for Pitcher List. His work has been featured on Baseball Prospectus, the Hardball Times, and October. He's still getting used to the DH in the national league. @seanroberts.bsky.social

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