Late-Season Arms (Kerkering, Leiter, Lopez, McKenzie, & Mederos)

Note: For the next few weeks, I’m going to focus on some pitchers who I thought were interesting but haven’t had time to dive in. Most were late-season debuts while others had an arsenal change. Others came of the IL as the season was coming to a close. I’m just going to work through them in alphabetical order and once done, I move to my normal late-round starters.

Orion Kerkering

The 22-year-old righty flew through the minors spending time at Low (10 IP) and High-A (20 IP), AA (22 IP), AAA (1 IP), and the majors (3 IP). He has closer material written all over him and won’t be an unknown after making seven post-season experiences where he threw more innings (5.1) than in the major league regular season (3). While in the majors, he posted a combined 11.9 K/9, he struggled with walks (5.4 K/9). In High-A, he posted a 2.7 BB/9 and 2.1 BB/9 in AAA, so walks weren’t always an issue.

He went with a heavy slider approach in the majors (85% usage) with the pitch averaging 87 mph and a 16% SwStr%. His sinker averaged 99-mph. Here are each pitch’s comps.

Even in their short sample, both pitches performed similarly to their comps.

With no set closer in the Phillies bullpen, Kerkering is a viable late-round Saves dart.

Jack Leiter

I noticed the Rangers had promoted Leiter to AAA so I wanted to see how his pitches graded out.

Pitch: Velo (mph), SwStr%
Four-seamer: 95, 9%
Slider: 85, 6%
Curve: 79, 25%

And here are their comps.

The two secondaries grade out as average with the fastball being a touch better.

Everyone, including the Rangers, would be higher on Leiter if he could get his walks under control. He’s always had a high walk rate over 5.0 K/9 at any level or season with the overall rate being 5.3 BB/9. He has the potential to be an ace if he can throw strikes.

Jacob Lopez

The 25-year-old lefty was a starter in AAA last season for the Rays and made four MLB appearances with one start. In AA last season he threw 28 IP with a 2.57 ERA (2.73 xFIP), 0.82 WHIP, and 14.5 K/9. In AAA, he struggled some over 79 IP with a 2.72 ERA (4.98 xFIP), 1.32 WHIP, and 9.9 K/9. In his 12 major-league innings, he posted a 4.38 ERA (4.54 xFIP), 1.30 WHIP, and 5.8 K/9. He was all over the place.

The only part of his arsenal to get excited about is his 79-mph slider with a 17% SwStr% in AAA and 25% in the majors. The MLB and AAA comps on the pitch have it performing more on the low side of the two options.

That’s it for the positives. He rounds out the arsenal with a 91-mph sinker he throws 56% of the time. His change had a 100% in-zone Contact rate. It wasn’t fooling any righties. They could probably see the ball pretty well because he has low arm slot from the first base side.

Right now, he seems to be a couple of steps away from contributing on a regular basis. I just see him shuttling back and forth between AAA and the majors.

Triston McKenzie

When McKenzie made two late-season starts, he and the team was deciding if he needed surgery.

Regardless of only having enough time for just two starts before the season came to a close, this was needed to prove that McKenzie was healthy enough to get back on the rubber. He visited multiple doctors over the summer after straining his elbow to determine if surgery was necessary. When he decided against a procedural route, it was hard to know for sure how he’d recover. For now, he’s demonstrated that he can pitch without surgery and he can now have a plan going into the winter.

They decided against going under the knife and he made a couple of starts. In them, his fastball velocity and Zone% were down compared to earlier in the season, but he has seen such rates before.

During his two late-season appearances, he threw 6 IP with 9 BB and just 1 K. That’s nuts.

Simply I’m out until he puts together three to four outings with no hint of injury and some idea of the strikezone. I feel others are going to prioritize him over me and that’s fine.

Victor Mederos

The 22-year-old Angel made 20 starts in AA but was recalled to the majors twice where he made a total of three appearances (3 IP). While in AAA, he posted a 5.67 ERA (4.73 xFIP), 1.48 WHIP, and 9.7 K/9 over 20 starts. Overall, he seems to be a high strikeout and walk arm.

To get the strikeouts, he has a 97-mph sinker. Even with the high velocity, his fastball isn’t missing many bats (5% SwStr%) even when I ran the comps. As for his secondaries, they both grade out as average.

Walks might remain an issue with a combined 4.3 BB/9 (40% Ball%, equivalent to 4.3 BB/9) in AA. He was still posting a 39% Ball% in the majors.

His non-fastballs aren’t good enough to overcome the lack of command but he could take a major step forward if he finds the strikezone.





Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR twice, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.

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Greggmember
3 months ago

To get the AAA pitch-level data, did you have to manually extract the data from Savant yourself or is there a good source for a pre-compiled dataset?