Red Sox MiLB Notes: Anthony Eyanson promoted, Hayden Mullins pushing for spot in Worcester, Franklin Arias’ bat red hot

It’s that time of year when organizations across baseball begin promoting prospects throughout their systems.

The Red Sox have already started that process, promoting right-handed pitching prospect Anthony Eyanson to Double-A Portland after an electric start to his professional career.

Eyanson, 21, posted a 0.44 ERA, allowing just one earned run on seven hits over 20 1/3 innings. The LSU product also racked up a staggering 34-to-3 strikeout-to-walk ratio.

In his final outing for High-A Greenville against Hub City, Eyanson allowed one hit and issued three walks, the first of his professional career, while striking out seven of the 15 batters he faced across 3 2/3 scoreless innings. He threw 67 pitches (37 strikes) and generated 11 whiffs.

Ranked as the Red Sox’ No. 13 prospect by Baseball America entering the season, Eyanson was selected alongside fellow 2025 draft arms Kyson Witherspoon (No. 4) and Marcus Phillips (No. 9). All three are in their first professional season, though Eyanson has separated himself early. Witherspoon owns a 7.13 ERA through five outings, while Phillips has posted a 5.87 ERA over 15 1/3 innings.

Eyanson features a fastball that sits 95–97 mph and has touched 98–99, along with an 86–88 mph slider, a cut-splitter, and a 79–80 mph high-spin curveball, according to SoxProspects.

Boston selected Eyanson in the third round of last year’s MLB Draft, and he’s stood out from the jump, dating back to the Spring Breakout Game against the Orioles in March. In that outing, Eyanson threw 14 pitches, touched 100 mph, and averaged 99.2 mph on five four-seam fastballs. His fastball, splitter, and curveball were all on display as he struck out all three batters he faced.

Eyanson now heads to Hadlock Field, where he’ll join the Portland Sea Dogs rotation alongside John Holobetz, Jedixson Paez, Gage Ziehl, Blake Wehunt, Hayden Mullins, and Shea Sprague.

The Red Sox recently added Sprague to Double-A Portland to bolster the Sea Dogs’ starting pitching depth. With six starters already in the rotation, and bullpen arms capable of being stretched into bulk roles, Sprague’s arrival could open the door for Mullins to earn a promotion to Worcester.

Sprague, 23, was selected in the 13th round of the 2024 MLB Draft out of North Carolina. While he doesn’t overpower hitters, sitting 89–91 mph with his fastball, he mixes in a changeup and slider, with the changeup standing out as his best pitch, particularly against right-handed hitters. Boston views Sprague as a versatile arm who can fill multiple roles while providing organizational depth as the Hanover, Mass., native continues to develop.

Mullins, meanwhile, appears to be next in line for a call-up and could provide a boost to a depleted WooSox rotation. Ranked as the Red Sox’ No. 22 prospect by Baseball America, the left-hander is coming off a strong 2025 campaign in which he posted a 2.21 ERA between High-A and Double-A, held opponents to a .175 average (sixth-lowest among minor leaguers with at least 100 innings), and recorded a 30% strikeout rate.

This season with Portland, Mullins has made four starts (five appearances), going 2-1 with 34 strikeouts to 14 walks, a 1.01 WHIP, and just one home run allowed over 22 2/3 innings. Early-season cold weather hasn’t done him any favors; he issued 13 of his 14 walks in April, including two starts with five walks. That stretch included his season debut against New Hampshire, when he lasted just 1 2/3 innings in 35-degree conditions with gusty winds at Hadlock Field, allowing five earned runs while walking five.

On April 19, Mullins was part of a combined no-hitter against Altoona, tossing six strong innings with eight strikeouts while allowing three hits, one walk, and hitting a batter. In his most recent start at Somerset, he followed that up with another dominant outing, six innings, 10 strikeouts, and just one walk. As the strikeouts pile up, Mullins continues to make a strong case for a promotion to Triple-A Worcester.

The WooSox rotation is currently depleted, with right-hander Jack Anderson and left-hander Eduardo Rivera the only true starters, both of whom are being held back due to Boston’s pitching situation. Sonny Gray is expected to come off the injured list and could return Wednesday for the series finale against the Tigers, while rookie left-hander Jake Bennett remains an option if Gray isn’t ready.

Worcester has also leaned on left-hander Michael Sansone, who has made three starts but has struggled of late, allowing six earned runs over his last 9 2/3 innings. At this point, the WooSox simply need innings. Right-hander Isaac Coffey has made four starts, posting a 4.61 ERA across 13 2/3 innings. Adding Mullins would provide a much-needed boost, with the staff also potentially leaning on arms like Seth Martinez and Angel Bastardo to fill out starts.

Mullins, who won’t turn 22 until October, could become the first of Boston’s 2025 upper-round pitching class to earn a promotion. He also profiles as a potential trade chip for a team in need of pitching later this summer, especially if the Red Sox fall out of contention and look to add organizational depth.

Another name to watch for a promotion is shortstop Franklin Arias, arguably the hottest hitter in the system. Ranked as the organization’s No. 2 prospect by SoxProspects, Arias has been on an offensive tear.

He launched his eighth home run in Portland’s 7-6 loss to Somerset on Thursday, capping a scorching April in which he slashed .359/.433/.731 with a 1.164 OPS and 20 RBI over 22 games.

“I think he's got freakish bat-to-ball skills, and what he's now learning, is that just because he can hit something, it doesn't mean he has to hit it,” WooSox hitting coach Johnny Reina said to Boston Sports Journal. “He’s finding a way to shrink the zone to where he wants to do damage at.”

Arias has just 32 Double-A games under his belt, but that hasn’t slowed the 20-year-old, who’s hitting everything in sight. Last season, Arias had eight home runs in 116 Minor League games, a total he’s already matched in just 20 games in April.

Earlier this month, he homered in three straight games, twice.

“His average exit velocity is up almost as up three and a half miles an hour as of a few days ago,” Ian Cundall said on the latest SoxProspects’ podcast. “His launch angle is up 12 degrees. His barrel rate is up like 20 plus percent and the thing that interests me almost more than this is his chase rate is down considerably. His swing and miss has stayed pretty static.”

Cundall added, “His chase rate in AA is down substantially from where it was last year. He's making better swing decisions, which is allowing him to access his power more because his problem was he would see so few pitches.”

Arias also added 10 pounds this offseason, and the added strength is clearly translating into a power surge at the plate.

“You're gonna continue to see all the hard work that he's put in throughout the off-season,” Reina said. “The kid's special… At some point, he's gonna be up here.”

Reina stays in touch with Arias, while allowing the Double-A staff to lead his day-to-day development. 

“You’ll touch base with Double-A staff, we have a really good staff there,” added Reina. “Obviously we trust everybody who's on our staffs to do their job and do their job well and be communicative. We have all these channels and stuff where we keep everything updated throughout the organization to keep tabs on players.”

Arias is an ascending prospect who should continue climbing Top 100 lists. Baseball America ranks him as the No. 2 prospect in the Red Sox system, matching SoxProspects, and No. 46 overall in baseball.

He’s also making a strong case for a promotion to Triple-A Worcester. There’s little blocking his path, with Vinny Capra and Tsung-Che Cheng currently handling shortstop duties for the WooSox. When Arias arrives in the Canal District, he should be the everyday shortstop, while becoming a fan favorite.

Left-hander Dylan Brown is moving from Low-A Salem to High-A Greenville, according to SoxProspects’ Chris Hatfield. The 6-foot-5, 230-pounder features a four-pitch mix: a 91–94 mph fastball, an 88–89 cutter, an 81–85 slider, and an 82–84 changeup. He’s pitching to a 2.31 ERA with 32 strikeouts to 13 walks over 23 1/3 innings this season and could rise quickly up prospect rankings over the next month.

Another name to watch, especially for those tracking pitching prospects, is left-hander Ethan Walker, whom the Red Sox drafted out of Kentucky last year. The 6-foot-2 southpaw also features a four-pitch mix, highlighted by a changeup and slider that missed bats in college. In an interview with SoxProspects’ Andrew Parker this spring, Walker said he prefers not to live in the zone, instead challenging hitters to try and square up his stuff.

"I would say I am unique and competitive," Walker said. "I feel like a lot of people say they struggle with seeing my pitches just because of how long I hide the baseball. Unique is the word I have heard a lot over the years. A lot of people say they haven’t seen my arm action and stuff like that before. I would also say I am a big competitor. I like competing more than anything. I don’t like pitching around the zone. I like throwing it and seeing if they can hit it. During my first years of college, I struggled with that. But, as I got to my junior year and realized how good my stuff was, it became a lot easier just throwing stuff in the zone."

While the big league club hasn’t inspired much confidence early this season, the farm system is stocked with intriguing talent, players who could impact Boston later this year or serve as valuable trade pieces if the Red Sox work their way back into the American League race.