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.

Po-Yu Chen

One of the Pirates' top international signings from the 2020-2021 off-season will likely be part of a stacked Double-A rotation. Behind Skenes, Chandler, Harrington, and possibly Solometo, you have Taiwanese right-hander Po-Yu Chen. Chen has shown promise at each and every level thus far and now will test his skill against upper-level competition.

Chen had a 4.44 ERA, 5.22 FIP, and 1.38 WHIP in 119.2 innings. Looking at those numbers, they're not very good, but take it with some context. Chen had a HR/9 of 1.68, but I would not take his home run rate at face value. Chen had a 20.8% HR/FB ratio in the home run-friendly confines of the Grasshoppers' park, First National Bank Field. Chen also had some other solid peripherals, including a 24.5% strikeout rate as well as an 8.5% walk rate. He also bombed his last four starts of the year, allowing 15 earned runs in his last 13 innings of work. His ERA went up from 3.71 to nearly four-and-a-half in less than two games worth of innings.

Chen is a command-focused pitcher, similar to Sullivan. He sits in the low-90s as well with a curveball and slider. He can throw all three for strikes. But he does have one plus pitch, and that's his splitter. It has fall off the table-like action. Chen is an advanced arm that stands at 6'2", 187 pounds.

Chen is the youngest player on today's list, as he just turned 22 in October. Given his age and the fact he's yet to throw a single pitch at Double-A, he has the least likely shot to make his big league debut, at least in my unprofessional opinion. But I don't think you can rule it out completely. Chen showed a lot of talent at Greensboro, even if the numbers don't reflect it. He's going to be overshadowed by his rotation compatriots, most of whom are top 100 or borderline top 100 prospects, but don't sleep on him just because he's Altoona's 5th best starting pitcher.

Tres Gonzalez

The 2022 draft saw the Bucs take outfielder Tres Gonzalez in the fourth round. Gonzalez made his debut late into the 2022 season, and while he looked good through his first 95 plate appearances, he would take another step forward in 2023. Now, he should start the 2024 season as part of Altoona's outfield.

Gonzalez received 531 plate appearances, most of which came at High-A Greensboro. He batted .289/.405/.402 with an outstanding 15.1% walk rate and 17.9% strikeout rate. Gonzalez isn't known for his power and only went yard nine times with an isolated slugging percentage of .113. But he used his speed to hustle out 22 doubles and steal 28 bases. All told, Gonzalez had a .381 wOBA and 128 wRC+. Gonzalez was just one of 21 batters in the minor leagues with at least 500 plate appearances and an OBP over .400.

Gonzalez takes a very contact and OBP-focused approach. Think of Adam Frazier but with more walks. There will be concern about how Gonzalez's power will play once he moves to the upper levels of the minor leagues next season. His exit velocity numbers were not good, though as long as he maintains a good walk rate and continues to hit the gaps, the approach could work.

An above-average defensive outfielder, Gonzalez saw time at all three outfield positions last year. He's plenty fast enough to cover ground in center field. That's also where his arm will likely play best at. A corner might expose his below-average arm strength, so putting him up the middle can hide that to a degree.

How Gonzalez plays at Altoona will determine if he could potentially make his debut. But his first extended look against pro pitching was very impressive. Should he continue to do this in Altoona, I wouldn't completely rule out a late-season cameo with the Pirates. At the very least, he has a chance to put himself into conversations for a role for the Major League team in 2025.