3 Rule 5 prospects Pirates should watch who dominate a key predictive stat

Even in today’s baseball, where highly advanced statistics are available to everyone with internet access, something as simple as strikeout rate minus walk rate still remains an easy predictor of future performance. With that in mind, it might be a stat the Pittsburgh Pirates should be using to evaluate who to take in the Rule 5 Draft, if they opt to select someone. The Pirates will have the fifth pick in this year’s draft, and they’ll have most of the field available to them on Wednesday. Based on K%-BB%, this is who they should have on their radar.

A simple stat that can tell a lot might be all the Pirates need to find a diamond in the rough in the Rule 5 Draft.

Jeremy Wu-Yelland

The Boston Red Sox drafted Jeremy Wu-Yelland in the fourth round of the 2020 draft. He began his pro career as a starting pitcher, but Tommy John surgery in April 2022 and another injury in 2023, which kept him out for most of that year, impeded his development. Wu-Yelland moved to the bullpen full-time in 2024 and had a strong breakout campaign this past season.

Wu-Yelland tossed 45.1 innings between High-A and Double-A, while posting a 3.15 ERA, 2.86 FIP, and 1.07 WHIP. The left-hander struck out an astounding 37.6% of batters faced with a quality 8.5% walk rate. That puts his K%-BB% at 29.1%, which is one of the highest marks in minor league baseball this past season. He ranked tenth in the stat among pitchers with at least 40 innings pitched. Some of the few names that ranked ahead of him are some of the best young pitchers in the minor leagues, like Travis Sykora, Chase Burns, Trey Yesavage, Payton Tolle, and Jonah Tong.

Wu-Yelland utilizes a three-pitch mix, headlined by a mid-90s fastball. He’ll also throw two breaking pitches: a low-90s cutter and a low-80s slider. He also dramatically improved his control. Wu-Yelland’s walk rate prior to Tommy John surgery was 12.8% in 2021. He then walked 14.5% of batters in 2024, before cutting that down below 10% this past campaign. 

Zach McCambley

Zach McCambley was named as one of the notable players in this year’s Rule 5 draft by Baseball America, and for a good reason. The right-hander is another former 2020 draft pick, as the Miami Marlins selected him in the third round. McCambley has flashed potential in the past, but 2025 was by far his best season.

He tossed 62 innings while working to the tune of a 2.90 ERA, 2.60 FIP, and a 1.10 WHIP between Double-A and Triple-A. McCambley nearly struck out a third of the batters he faced, with a 33.1% K%. While McCambley walked over 12% of batters he faced every season from 2022 through 2024, he only dished out a free pass 8.8% of the time this season, resulting in a K%-BB% of 24.3%. Once again, this was among the best marks in the minors, ranking 23rd among minor league hurlers who threw at least 60 frames this past year.

McCambley isn’t an overpowering pitcher, as his fastball sits 94-95 MPH, and his sinker sits low-90s. His go-to breaking pitch is a low-80s slider that batters couldn’t touch at Triple-A, with a whiff rate of 50.7%. McCambley will also throw an upper-80s cutter and a low-80s curveball to round out his pitch arsenal. 

Andrew Baker

The Philadelphia Phillies left a pitcher available who has elite-level stuff and a bottom line that doesn’t tell the whole story. Andrew Baker was an 11th-round pick by the Phillies, and has struggled badly in the past to keep his pitches in the zone. However, 2025 was his most promising season by far, and the Phillies left him open for the taking.

Baker’s 4.86 ERA in 53.2 innings between High-A and Double-A does not tell the whole story. He had both a 3.19 FIP and 2.99 xFIP, and his ERA was inflated by a .384 batting average on balls in play. Baker struck out 29.8% of batters he faced with a sub-10% walk rate, clocking in at 9.9%, culminating in a K%-BB% of 20.4%. That may not look as impressive compared to Wu-Yelland or McCambley, but out of the over 1,300 minor leaguers who threw at least 50 innings, he was among the top 150.

Plus, his stuff is way better than either McCambley’s or Wu-Yelland’s. There was never a question about whether Baker had the ability to be an elite pitcher in the future. His fastball sits 97-100 MPH. Baker is primarily a three-pitch pitcher, as he complements his heater with a mid-80s sweeper and a low-80s curveball. Baker’s previous career-low single-season walk rate was 12.3% in 2022, so cutting it below 10% is a massive improvement for him.