Pittsburgh Pirates: One Underrated Prospect At Each Position

Who is the best underrated prospect at each position in the Pirates' system?
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Starting Pitcher - Sean Sullivan

The Pirates took right-handed pitcher Sean Sullivan in the 8th round of the 2021 draft. While the right-hander had a poor ERA at Greensboro in 2022, he struck out a decent amount of batters with a quality walk rate. Home runs gave him some trouble, but with an unsustainable HR/FB ratio, Sullivan was surely in for a better season in 2023.

Sullivan pitched 113.2 innings at Altoona, working to a 3.88 ERA, 4.16 FIP, and 1.27 WHIP. While Sullivan's strikeout rate dropped from a hair over 25% to just 20.4%, his walk rate remained at 8%, while his HR/9 rate fell to 1.03. Sullivan is a fly ball pitcher who had a fly ball rate over 50%. However, he induced enough soft contact to post a quality HR/9. The right-hander was much better at limiting home runs in the second half of the year, as his HR/9 went from 1.44 prior to the All-Star Break to just 0.53 afterward.

Sullivan has an interesting motion. He starts his arms low in his wind-up and looks almost like a side-arm hurler but then goes back to a three-quarters arm slot. However, he brings it back up to a more traditional three-quarters arm-slot. Sullivan sits 92-94 MPH, and he does have a solid slider. His change-up also looked quite decent. Sullivan has good command over his stuff as well.

The right-hander is going into just his age-23 campaign but will have made it to Triple-A Indianapolis. Sullivan is unranked by both FanGraphs and MLB Pipeline and excluded from each Pirates' top prospect list. However, he definitely could get a couple of starts next season.