An increased fastball velocity, and a more dynamic Clayton Kershaw

Clayton Kershaw has looked excellent in three of his four starts this season, and the main topic of conversation before, during, and after each of those outings has been his increased velocity on his fastball.

Thursday’s dominance in Seattle, in which Kershaw struck out 11 in seven innings, featured his fastball less than any other start this season, but also showed the importance of what the increased velocity brings.

Kershaw this season is averaging 91.8 mph on his four-seam fastball. Of the 91 major league pitchers with at least 20 innings in 2020, Kershaw ranks 63rd in fastball velocity. So he’s not blowing people away. It’s almost like there’s something more to pitching than speed.

But that 91.8 mph is a mile and a half better than last season for Kershaw, which was the lowest of his career. It represented a fourth straight season of declining fastball velocity, which makes this season’s resurgence all the more rare.

David Adler at MLB.com wrote about Kershaw’s uptick in velocity this season:

To put Kershaw’s velocity inflection in context, MLB Statcast database guru Jason Bernard looked at all instances in the pitch tracking era (since 2008) of a regular starter losing fastball velocity for four or more years in a row. Only a handful were able to break the downward trend and regain any velocity at all. None added back as much velo as Kershaw.

A benefit of the boosted fastball is the increased difference in speed between that and Kershaw’s slider. If the pitches are too similar, it makes it easier for batters to react to one or the other depending on what they are expecting. There’s a 4.1 mph difference so far this season between Kershaw’s fastball and slider, up from 3.4 mph last year and 2.8 mph in 2018.

“It just gives him a little more oomph, but I also think that it allows the slider to keep the velocity and the break on it,” pitching coach Mark Prior said Thursday. “The arm speed helps him lock in his really good slider.”

Kershaw on Thursday threw 42 sliders and got 12 whiffs on that pitch alone. In his first three starts this season Kershaw averaged 12 swinging strikes total from all his pitches combined.

“It’s a more dynamic Clayton,” manager Dave Roberts said. “What he’s doing with the slider sets the tone for everything.”

Kershaw also threw a season-high 21 curveballs, which the Mariners were taking a lot for what he called “free strikes.” Kershaw finished off four strikeouts with a curveball called for strike three.

“Your stuff sometimes comes and goes, but your ability to compete and your ability to manipulate through your through games and figure out different ways to get outs, ultimately that’s what wins games,” Kershaw said. “I’m thankful that my stuff has ticked up a little bit this year, and I’m going to pitch as long as I’m having fun. I’m having a ton of fun, and I don’t see that stopping anytime soon.”