Pittsburgh Pirates: Three Underrated Prospects Who Could Debut In 2024

Sean Sullivan

Sean Sullivan was an 8th-round pick by the Pirates in 2021. Taken out of the University of California Berkeley, Sullivan has steadily made his way up the Pirate system. After his quality season in 2023 with Double-A Altoona, Sullivan should start his age-23 season for Triple-A Indianapolis. If he pitches like he did for Altoona last year, especially in the second half, Sullivan could definitely find himself in the Pirates' rotation at some point.

Sullivan pitched 113.1 innings for the Curve while owning a 3.88 ERA, 4.16 FIP, and 1.27 WHIP. Although Sullivan's strikeout rate of just 20.7% was below average, he had an above-average walk rate of only 8%. After posting a HR/9 approaching 2.0 in 2022 for Greensboro, he cut that down significantly to just 1.03, which was also above average. Some of that is due to better flyball luck, as his HR/FB ratio dropped from an unsustainable 26.7% to 7.6%. Although Sullivan became more flyball-heavy, he did cut his line drive rate down from 28.9% to 13.5%.

As stated earlier, Sullivan was pretty good in the second half of the season. From the all-star break onward, the righty had a 3.53 ERA, 3.55 FIP, and 1.24 WHIP. While Sullivan still carried a similar 20.9% K-rate and 9% walk rate, he rarely allowed a home run. This was a stretch of 51 innings where just three batters were able to go yard off of him, leading to a HR/9 rate of 0.53.

Sullivan isn't a hard-throwing pitcher, only averaging out around 92-94. He also throws a slider, change-up, and curveball, but everything probably sits at a 45-50 grade level. While nothing in his pitch mix stands out, all his pitches are playable because of his ability to locate effectively and consistently.

Triple-A Indianapolis could have a very good rotation early on into the season, with Sullivan being a part of it. He's only 23, but I definitely think he could get at least one start by mid-season, so long as he continues to pitch like he has thus far in his pro career.