Pittsburgh Pirates: Three Pitchers to Watch in 2024 Based on Stuff+

Colin Selby

Colin Selby entered the season as one of the Pirates’ best relief prospects. Selby’s sinker was his primary pitch and was above average in the eyes of stuff+, coming in at 106. The right-hander has velocity on his side as he threw his sinkerball at 96.6 MPH on average, making it the 35th hardest-thrown sinker last year. His curveball, which he threw 17.2% of the time last year and came in around 82-83 MPH, registered at 109 in stuff+. Selby’s curveball had really good movement, with 55.3 inches of drop and 12.1 inches of break. That’s extremely comparable to Aaron Nola’s curve.

Of the pitches Selby threw with some regularity, his slider graded out the best in stuff+, coming in at 127. The reliever threw his slider at 88.4 MPH, the 54th hardest thrown of its kind last year. Selby’s slider had below-average vertical movement at 31.1 inches of drop, but with 6.1 inches of horizontal break, his slider broke just over two inches more than the average slider. Overall, Selby had 114 stuff+.

Selby’s stuff looked good, but he did not perform well. In 24 innings, he allowed 24 earned runs. While he struck out 26.3% of the opponents he faced, he also walked them at a 13.2% rate. Home runs gave him some trouble as well, as he had a 1.50 HR/9. Selby struggled, but there were some promising underlying numbers.

Selby had a 48.5% ground ball rate along with an above-average 88.1 MPH exit velocity. His .385 batting average on balls in play indicates he could probably regress toward the mean. Throughout the minor leagues, he held opponents to a .284 BABIP. Selby also had a 21.1% HR/FB ratio despite having a sub-30% fly ball rate. Selby had a 3.94 xFIP, 4.25 SIERA, and a 94 DRA- (203 ERA-), which point to average to slightly better than average production.

Hunter Stratton

Hunter Stratton was a former 16th-round draft pick who made his debut in 2023 and didn’t look bad when he arrived in the big leagues. Stratton’s primary pitch was his cutter, which he used about 50% of the time. The pitch is a low-90s offering but averaged out just a touch over 2700 RPM. Although his cutter had a slightly below-average drop, he had 5.8 inches of vertical break, the seventh-highest average vertical break among any cutter from any pitcher (min. 50 pitches). Stuff+ pinned his cutter at 109.

His best pitch per stuff+ was his four-seam fastball at 122. He threw this pitch around 96 MPH and approached 2600 RPM on average (2576 RPM, to be exact). Although Stratton’s fastball had good spin and speed, he didn’t take full advantage of either. His active spin rate on his four-seamer was just 73%, which caused his four-seamer to have below-average movement. Still, because of its velo, plus-plus spin rate, and lower release point, it plays up to a degree.

Stratton used his slider the least often in his brief big league debut and came out with a 113 stuff+. A mid-80s pitch, the righty reliever averaged 2759 RPM with the offering. Unlike with a four-seam fastball, the lower the active spin rate on a slider, the better, and Stratton averaged just 44%. This gave it 10.9 inches of horizontal break, which would have been top 30 had he pitched enough to qualify.

Although Stratton’s time in the Majors was brief, he pitched well in the 12 innings he tossed. Stratton only allowed three earned runs and just three walks to the 47 batters he faced. He may have only struck out ten, but he had a 51.5% ground ball rate.

After being designated for assignment by the Pirates in November, Stratton returned on a minor league contract in early December. Stratton will begin the season back at Triple-A Indianapolis, but could see time in the majors once again.

Jackson Wolf

The Pirates acquired left-handed pitching prospect Jackson Wolf last trade deadline. You wouldn’t think that a guy who averages 88-90 MPH would be on a list like this. Stratton and Selby are hard throwers. But in Jackson Wolf’s lone MLB start, he registered a stuff+ of 117. All three of the offerings he used registered as above average. That ranged from 107 at worst to 132 at best. That’s only 1% worse than David Bednar and 1% better than San Francisco flamethrower Camilo Doval.

Once you dig into some of his pitch metrics, you can kind of see why he is so highly regarded in the eyes of stuff+. He may only sit 88-90 MPH with 2108 RPM on his fastball, but with an active spin rate of 96%, he throws his four-seamer with above-average vertical and horizontal break. With 12.9 inches of horizontal movement, Wolf would have been among the top 20 fastballs had he thrown enough to qualify. Overall, Wolf’s fastball sat at 107 in stuff+.

Both his slider and changeup have slightly below-average movement, but they were even nastier per stuff+ than his fastball, which arguably had better qualities. However, that’s probably because of his release point. Wolf’s extension comes out to about seven and a half feet, making his velocity way up. The second reason is because of his side-arm-like arm slot, which sat around five feet. The lefty also had just a 2.91-foot horizontal release point. Wolf’s slider had a 120 stuff+ rate, while his change-up clocked in at 132.

Overall, Wolf pitched well in Double-A, working to a 4.13 ERA, 4.02 FIP, and 1.11 WHIP. He held opponents to a .226 batting average while striking them out at a 26.8% rate. His 1.23 HR/9 was slightly below average, but he also was great at limiting walks with a 6.4% walk rate. But there was one start where he allowed eight earned runs in just 3.1 innings. Outside of this one game, he had an ERA of just 3.65 while his WHIP would drop to 1.04, and both his strikeout and walk rate would move in the right direction to 27.7% and 6.2%, respectively. Wolf also struggled through his final four starts of the season. Going into August 30th, he had a 3.81 ERA, 3.73 FIP, and 1.05 WHIP with a strikeout rate approaching 30% (29.3%) and a sub-7% walk rate (6.6%).