Going Deep: The Most Improved Pitches of 2018

Examining changes to the repertoires of pitching breakouts.

(Photo by Frank Jansky/Icon Sportswire)

It’s early in the season, and for the most part sample sizes are too small to draw meaningful conclusions. However, making fundamental differences to a pitch or changing approaches entirely are hard to fake. In this piece, I’ll be highlighting some of the most improved pitches of the new season.

Curveball: Nick Pivetta (SP, Philadelphia Phillies)

Pivetta’s curveball was a fairly mediocre pitch in 2017, allowing a 120 wRC+ with average movement at 5.3 inches of vertical drop. With a sterling 1.27 FIP through three starts in 2018, a revamped curveball has been the primary catalyst of this stretch of success. Among qualified starting pitchers, his new curveball ranks sixth overall with 10.9 inches of vertical drop, one spot behind Clayton Kershaw. The improvements in this pitch’s movement since last season have been dramatic:

It would make for a remarkable coincidence that the best three curveball performances of Nick Pivetta’s young career have come consecutively in his first three games of the 2018 season. This has potential to be an high quality pitch and gives Pivetta a third consistent offering in his repertoire, alongside a 95-mph fastball with life and slider which gave up a 44 wRC+ last season with a 17% swinging strike rate. Pivetta has all the tools of a top of the rotation starting pitcher if these changes stick and he continues to locate.

Slider: Trevor Bauer (SP, Cleveland Indians)

After using a slider as his primary off-speed pitch in 2014-15 to poor results, Bauer only threw the pitch occasionally in 2016-17. The version he mixed in last season was actually very effective, generating 20.6% whiffs and holding batters to a 56 wRC+. Bauer still reworked the pitch over the offseason, reportedly in the mold of Corey Kluber’s – one of the best in baseball. The version he’s shown this year has some additional life:

The spike downwards in the middle of the chart is from a game where Bauer only threw his slider twice, but other than that this is the most movement he’s ever had on the pitch. He’s thrown this slider 20.5% of the time so far this year, making it the third offering behind his fastball and curveball. It’s been absolutely dominant, allowing a -48 wRC+ (yes that’s negative) with a 66.7% groundball rate and 16.1% swinging strike rate. Watch out for a career year from Bauer.

Changeup: Mike Foltynewicz (SP, Atlanta Braves)

Foltynewicz has a place on this list not because of a fundamental difference in his changeup, but rather how he’s using it. This pitch has always had good movement: batters have whiffed at a 18.0% rate against it over his career. However, it’s still given up a 148 wRC+ and 31.3% line drive rate. Some of the blame for this hard contact can be assigned to poor location:

Foltynewicz has often left this pitch hanging over the middle of the plate and had it crushed by opposing hitters. The whiff rate indicates it can be a strong pitch with some adjustments though. We’re dealing with a small sample size here, but his 2018 strike zone heatmap is markedly different:

Falling out of the strike zone is a much more ideal location for a breaking ball to be located. In the 33 times Foltynewicz has thrown a changeup this year, batters have yet to record a hit for a perfect -100 wRC+ allowed and pVal/100 of 3.45 that ranks 21/75 among qualified changeups. It’s still inducing swinging strikes 15.4% of the time, so those with shares in Foltynewicz have to hope he continues to locate his changeup around the lower part of the strike zone.

These pitchers are poised for breakout seasons if they can maintain these new levels of performance. Not only is each performing well early on, but they all have made tangible adjustments that back it up. Keep an eye out on the charts to see what happens next.

Alex Isherwood

Creator of @ProspectBot and former FantasyPros writer. Studying computer science and mathematics at William & Mary.

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