Taillon’s Slider is Evolving, Helping His Other Pitches

Jameson Taillon has been one of the best starting pitchers in the game over the last three months. Since May 27, he is in the top 20 among qualified starting pitchers in ERA (3.04, 18th), FIP (3.12, 14th), innings pitched (94.2, 20th) ground ball rate (48.7%, 19th) and home run/fly ball ratio (8.8%, 19th). Call it cherry picking if you want, but no other starting pitcher in baseball is in the top 20 in all five categories, and only the Phillies’ Aaron Nola cracks the top 30.

That’s a stark turnaround from earlier in the season. While Taillon opened with three strong starts, he went in a seven game rut shortly after. Just to compare, here are Taillon’s stats before and after May 27:

Before May 27: 10 Games, 5.11 IP per start, 4.56 ERA, 4.17 FIP, 3 K/BB, .308 wOBA

After May 27: 15 Games, 6.31 IP per start, 3.04 ERA, 3.12 FIP, 3.6 K/BB, .292 wOBA

May 27 may seem like a fairly arbitrary date, but that is the day Taillon said his season started to turn around by throwing a slider.

“I think guys basically said ‘He has two pitches,’” Taillon said on his early season approach. “‘I don’t think we can hit the curveball, don’t want to hit the curveball, so let’s just toss that out and let’s look for a fastball out over [the plate].’

“Now, I feel like having the slider is protecting my fastball because I can throw it on hitter’s counts, and it’s helped my curveball because those two should play off of each other really well.”

Taillon offered a few samples of his newfound slider earlier in May, but he used it early and often against the Cardinals on the 27th, throwing it 30 times over his 6.1 innings of three run ball. Since then, he has used it at least 10 times a start and has not allowed more than three earned runs in an outing.

Finding early success with the pitch encouraged Taillon to do some experimenting with grips and delivery.

“At first, the way I was throwing it was more of a cutter mentality,” Taillon said. “Like not really turning it over at all and really just like an aggressive fastball mentality pitch.

“Now, I’m learning the difference between making it the cutter-y hard, 91, 92 [MPH] pitch and the backdoor slider with depth and a little bit of wrist action on it. So I am starting to experiment a little bit between the two.”

It’s easy to find evidence of that experimentation by looking at the fluctuations in his spin rate per start, but there is a clear trend upwards. Going by month, Taillon’s slider averaged 2,287 RPM in June, 2,421 RPM in July and 2,450 RPM through his first three starts in August.

He averaged 2,550 RPM in his last outing on Aug. 19- the highest its been in any start since he started throwing it consistently.

For reference, his median slider comes in at 2,379 RPM this year.

That extra spin has created more whiffs. Per Baseball Savant, when Taillon’s slider has a release rate of 2,400 RPM or more, batters swing and miss 18% of the time compared to 13.9% when it’s 2,399 RPM or less.

Adding in variety and changing the eye level has helped most of Taillon’s other pitches, too. Since May 27, his two-seam fastball, curveball and changeup have yielded better results.

“Now I’m throwing more heaters up, so the curveball’s helping, and I’m throwing sliders on the same plane as my fastball,” Taillon said. “It’s all kind of blending together and making hitter’s decisions a little tougher.”

To illustrate Taillon’s point, Pitcher List’s Michael Augustine made a great GIF overlay of the plane his two fastballs and slider take.

Taillon attributes the improvement in his changeup from being able to throw it less. He threw it 74 times his first 10 starts (8.7% of his pitches), but just 54 times since the slider came into play (3.8%).

Even though its whiff rate has taken a steep drop, batters are just 2 for 11 with two singles on at-bats ending with a changeup over the last three months.

“When I am throwing it, it’s a very clear situation where it plays,” Taillon said. “I’m not forcing it in as much anymore...When I do throw it, it has a purpose.

“The slider takes the place of the changeup from time to time where I can throw it behind in the count, get back in the count.”

Taillon having that fourth pitch now gives him the ability to throw different pitches with purpose more rather than necessity, which has yielded better results across the board. What’s left to be seen is how its evolution will impact his performance going forward.