Thoughts on Twins prospect Kohl Stewart

As I write this, Kohl Stewart is about to make his major league debut for the Minnesota Twins. Stewart was their first-round pick back in 2013 but his road to the majors hasn’t been particularly smooth. Let’s take a look.

From high school in Houston, Texas, Stewart was widely considered to be the top high school pitcher in the ‘13 class. Selected fourth-overall, he was viewed as a hard-throwing fireballer in the Texas tradition and a possible top-of-the-rotation starter.

He was reasonably successful in the lower minors with pleasant ERAs (2.59 in Low-A, 3.20 in High-A) although his pitching style was different than originally expected. His 2016 season was solid enough, 2.88 ERA in 144 innings between High-A and Double-A, although his ratios slipped substantially after his promotion.

The last time I wrote a full report on Stewart was for the Twins 2017 list, which went like this:

11) Kohl Stewart, RHP, Grade B-: First round pick in 2013 from high school in Texas, went 12-8, 2.88 in 144 innings between High-A and Double-A; allowed 130 hits with 91/63 K/BB; red flag here is poor 47/44 K/BB in 92 innings after moving up to Double-A; you can make a case as high as number five or six but the lack of strikeouts continues to concern me; has low-90s power sinker along with curve, slider, and change-up but quality of secondaries and overall command can be erratic; on the right day looks like a number two starter but on the wrong one he looks more like a middle reliever

Stewart’s 2017 season was rather mediocre, with a 4.28 ERA in 82 innings and a blahish 57/46 K/BB in the high minors. I had Stewart rated as a Grade C+ prospect entering 2018 but he fell outside the Twins Top 20.

Listed at 6-3, 195, Stewart is 23 years old now, so while he didn’t arrive as quickly as hoped he’s not old by any means for a prospect. Although the report above was written for ‘17, the basic take still stands: Stewart looks terrific on the right day but has problems with consistency.

There are several components here. He’s had issues with nagging injuries, including shoulder, hamstring, and thumb injuries in high school, more shoulder trouble in ‘14, elbow tenderness in ‘15, and a sore knee that bothered him much of last season.

The fastball that was 95-96 in high school has settled into the low-90s as a pro. His plus high school slider has regressed but his change-up and curveball have reportedly improved. The Minneapolis Star-Tribune has a good article on Stewart today, detailing the changes he’s made including the adoption of a one-seam fastball this year. There’s more here in this interview:

Overall this year he has a 4.47 ERA in 109 innings between Double-A and Triple-A with a 101/33 K/BB and 129 hits allowed. His strikeout rate has risen and his walks are down, good signs, and he’s maintained a strong ground ball rate. There are still issues with start-to-start consistency, however. I’ve thought in the past that he would be more dominant if used in the bullpen but the Twins still see him as a starter.

All-told Stewart looks like a number four starter at this point, with his grade still hovering on the B-/C+ boundary.