Mitch Keller: Fastball's value boosted by secondary pitches

A look at how Keller turned his fastball from one of the worst pitches in his rookie year, to one of the best in 2023.

Photo Credit: WTM

It’s been a wild ride following Mitch Keller's career. Going from second-round pick out of Iowa to one of the top pitching prospects to statistically one of the worst pitchers in the majors before finally making the All-Star game last year.

Now he has a contract extension in hand and will be in a Pirates uniform for at least the next five years.

Thursday, the Pirates announced a five-year extension worth $77 million extension for Keller.

Going back to 2023, of the 44 ‘qualified’ starting pitchers last year, Keller finished eighth in innings pitched, 10th in strikeouts, 17th in xFIP, and 23rd in WAR.

Keller, 27, is a fantastic story on prospect development and making the proper adjustments to become a successful pitcher at the major league level.

He’s had to completely revamp his pitch arsenal, adding in a sweeper and sinker, the latter was rated as his best pitch regarding run value on Baseball Savant.

When looking at Keller, yes, the insane break that he gets with the sweeper (averaged 18” of horizontal break) is nice, but the success he got with the fastball is really impressive.

During his rookie year back in 2019, Keller’s four-seam was one of the worst in all of baseball. It had a run value of -11, produced just a 17.5% whiff rate and his opponents slugged .719 (.460 xSLG) against it.

Savant credits him with throwing just the fastball, cutter, curveball and change-up back in 2019.

He’s since evolved to throw a sweeper, cutter, and sinker.

With all of the pitches tunneling off of each other, that’s allowed the fastball to play up a lot more, and his success with it in 2023 was almost a complete 180 from where he was at in 2019.

Opponents hit just .176, slugged .351, and generated a whiff rate of over 30% (30.2%). He used the four-seam nearly 50% of the time in 2019, compared to just 26.5%, picking and choosing his spots better.

What’s even more impressive is that he still generated a near 30% (27.5%) whiff rate of swings in the strike zone.

It’s been precise location for Keller, picking his spots rather than overpowering hitters. Only Logan Webb and Chris Bassitt picked up more called strikes than him.

While Keller’s strikeout rate was in the 65th percentile last year, his whiff and chase rate were only in the 26th and 29th, respectively.

This is now the third straight season that the Pirates have extended one of their own players to long-term contract, and the second that was drafted and developed from within.

There may be a lot of questions about the starting rotation going into 2024, but Keller isn’t one of them.