Prior to the 2024 season, the Boston Red Sox were marketing the future through a collective group of prospects that had the public excited. Roman Anthony, Kyle Teel, Marcelo Mayer, and Nick Yorke (with Kristian Campbell replacing him during the season) were being advertised as the “core four”; in a sense, being seen as the future of the organization.
Fast forward two seasons, and while they aren’t being marketed in the same vein, the Red Sox may have their next quartet, but this time from a pitching standpoint instead of hitters.
Since taking over, Craig Breslow has revamped the Red Sox pitching development system and, through the drafts, has focused on pitching as 28 of his draft selections have been pitchers. The team has used the influx of pitchers to completely overhaul its depth, and the surplus of pitching has allowed it to move multiple pitchers to improve its major league roster.
Despite that, both Breslow and the Red Sox have decided upon four pitchers that are seemingly high on their list. Of the four, three of them were taken in last year’s draft. Kyson Witherspoon, Anthony Eyanson, and Marcus Phillips were taken with three of the first four Red Sox picks. The final member of the quartet, Juan Valera, was signed as an international free agent back in 2023. Together, these four have the potential to become the team’s next “Big Four” once Payton Tolle and Connelly Early graduate from prospect status. Though that’s not to say they haven’t already been making headlines for themselves within the first week of spring training.
Kyson Witherspoon
Witherspoon, viewed highly by the organization, has already turned heads since the offseason began, thanks in part to his work ethic. Having spent time with Driveline over the winter, Witherspoon was able to learn a sweeper to add to his arsenal. What makes his new sweeper fascinating is that he was able to get 20” of horizontal break on it, something that no other Red Sox prospect was able to do in 2025. Along with that, there were fewer than 10 pitchers in all of minor league baseball who had a sweeper with at least 20” of horizontal movement.
Add to it a fastball that averages in the mid to upper 90s, and Witherspoon could fly through the minors in a way similar to Tolle. So far in spring training, Witherspoon has thrown live at-bats twice, getting his fastball up to 97 mph in the first session back on February 13 and hitting 98 mph on February 20. In the latter, he pitched against Roman Anthony, getting him to ground out.
Now, spring training is still young, and it makes sense for pitchers to be ahead of hitters, but the Red Sox are high on him. As reported by Alex Speier, there’s a real possibility that Witherspoon could start the season in Double-A instead of High-A like most first-round picks with the Red Sox. Witherspoon is viewed as a Top 100 prospect for several publications, and his work ethic and growth in just under a year with the organization are remarkable.
Juan Valera
Joining Witherspoon in conversations about dominant, intriguing, young pitchers is Valera. Valera, who won’t turn 20 until the middle of May, has been viewed as one of the better Red Sox pitching prospects since 2024, when he made his stateside debut in the Florida Complex League. After throwing 40 1/3 innings with a 1.79 ERA, he was promoted to Salem, where his dominance continued with 28 strikeouts in 23 innings. The team was impressed with his performance across the two levels and was slated to open 2025 with Greenville. Unfortunately, Valera struggled at times to pitch deep into games, making it into the fifth inning only three times. Despite that, he was dominant at times and only allowed more than two earned runs twice. The hard-throwing right-hander missed most of the season after dealing with elbow soreness in May.
Despite that, Valera showed up to spring training ready to show what he could do. Backed with one of the hardest sweepers in all of minor league baseball (thanks to it having a spin rate over 2,700 rpm and a fastball that can top out at 100 mph, Valera has two deadly pitches to work with. Much like Witherspoon, Valera has also cracked some Top 100 prospect lists, ranking 90th in ESPN’s selections.
Valera is a prospect whose value will be tied to his health. Through his first three professional seasons, the right-hander’s max number of innings thrown was 63 1/3 in 2024. How he handles a full season’s workload will help tell what kind of pitcher he could end up becoming.
Currently, though, it’s one with extreme talent, as backed by Anthony. Much like with Witherspoon, Valera faced Anthony in a live at-bat. In it, Valera attempted to attack Anthony, and while the outfielder managed to make contact and foul a pitch off, he would eventually be struck out while looking at strike three. After the at-bat, he asked SoxProspects’ Andrew Parker what level Valera was at, eventually saying, “This kid is really good”.
For him to reach his potential, however, it’ll be about going deeper into games. Already, he’s shown an ability to strike batters out and generate whiffs, but he needs to learn how to get batters to hit for soft contact instead of attempting to strike everyone out.
Marcus Phillips
The third member of the quartet may be the biggest boom-or-bust prospect of the group, as Phillips has a high ceiling thanks to his size and athleticism paired with his fastball’s velocity. Drafted with the pick acquired in the Quinn Priester trade, Phillips already topped out at close to 101 mph in college. The right-hander demonstrated two potentially above-average pitches in college with his fastball and slider, while his changeup could potentially be an average pitch.
Unfortunately for Phillips, the biggest issue with his delivery that could see him become a bullpen arm is his ability to throw strikes. Despite those concerns, Phillips had a walk rate of 9% in his first season as a starter in 2025, and his build alone will lead the Red Sox to begin his development in the starting rotation. Standing at 6-foot-4 and weighing 245 pounds, he is another big and strong pitcher that Breslow has craved since overhauling the organizational pitching development.
2026 will be huge for Phillips to determine the path the Red Sox decide to take with him. Phillips very likely could be the equivalent of Nick Yorke in this scenario and end up traded due to others passing him on the organizational depth chart, or he could end up being the best of the four pitchers.
Anthony Eyanson
The final member, Eyanson, could end up being the best because teams overlooked him at the draft. Taken by the Red Sox in the third round, there’s no debate that Eyanson could have been a first-round pick with his potential, especially after finishing third in Division I in strikeouts and previously being a consensus top 50 prospect before falling to the Red Sox in the third round.
While it can be argued that Eyanson could very well be a high-floor, low-ceiling pitcher, his attitude to improve and his chip on his shoulder after falling in the draft could lead him to push past those projections. Last week, Eyanson threw a live at-bat on Friday, February 20, and in that session, he was told he topped out at 98.4 mph. When he was in college, he was averaging 92-94 mph, already showing improvement in his velocity. From a visual standpoint, he also looks stronger, having put on muscle since being drafted, as he aims to prove all the doubters wrong.
His pitch arsenal alone seems to have three potentially above-average pitches in his fastball, slider, and curveball, while his changeup could end up being an average pitch at the major league level. Eyanson is likely to stick in the rotation thanks to his athletic frame, strong makeup, and his tendency to be a hard worker.
The Red Sox have managed to surround their lower levels of the minors with intriguing pitchers who could very well help the major league team as soon as the 2027 season, depending on their development. Over the last few years, fans were able to watch minor league hitters with excitement, and now it’s flipped to the pitching side as the team very likely has its new Big Four. It’ll be a fun season watching these four pitchers develop and move through the minor leagues, as fans can’t help but visualize a pitching staff featuring them.