Red Sox to promote hard-throwing relief prospect Ryan Zeferjahn to Triple-A Worcester

Among 127 pitchers in the Eastern League who have accrued at least 10 innings to this point in the season, Zeferjahn ranks sixth in strikeouts per nine innings (14.49), 20th in walks per nine innings (1.98), fifth in strikeout rate (40.7 percent), 21st in walk rate (5.6 percent), 30th in batting average against, 16th in WHIP (0.88), 29th in swinging-strike rate (14.6 percent), first in ERA, second in FIP, and fifth in xFIP (1.76), per FanGraphs.

In a recent conversation with Smith, Zeferjahn revealed that he spent most of this past offseason working out at the JetBlue Park complex in Fort Myers and lost approximately eight to 10 pounds “by dieting and hitting the weight room hard”. He now stands at 6-foot-5 and 230 pounds as a result of having “better weight” on him.

“I knew it was going to be a big year for me,” Zeferjahn explained. “I needed to show that I was putting in the work. And it’s starting to kind of pay off.

“I’m 26 now, which is not necessarily old for baseball but in the minor leagues, people think it’s old,” he continued. “But honestly, this is the best I’ve ever felt. I’ve kind of been hurt every year coming up and whatnot. Just knick-knack injuries that kind of set me back on what I really could show. This year, my body is in a better place. I’m going to show what I really have. I think I’ve done that. I know the work I’ve put in and the stuff I have. … Honestly, I’m not a prospect anymore. But I’m going to be there. I’m going to do my best to try to help the big-league club.”

Zeferjahn was originally selected by the Red Sox in the third round of the 2019 amateur draft out of Kansas. The former Jayhawak signed with Boston for $500,000 and made his professional debut as a starter but has since transitioned to the bullpen on a full-time basis. He has struggled with his command in the past, evidenced by a 5.02 ERA (5.44 FIP) in 34 outings (43 innings) for Portland in 2023, but he made strides over the winter to address that.

“The focus for him was throwing strikes, being competitive in the zone,” Red Sox director of player development Brian Abraham said of Zeferjahn when speaking with The Boston Herald’s Mac Cerullo last month. “It’s only been a short amount of time this year but he’s done that.”

For his part, Zeferjahn told Smith that he has “bought into” the new pitching infrastructure laid out by Red Sox chief baseball officer Craig Breslow and pitching coach Andrew Bailey. One of the many philosophies embedded within that infrastructure is to simply throw more strikes.

“I’m willing to try anything,” said Zeferjahn. “I really bought into Bailey and Breslow and what they’ve kind of brought in. It started from the top and they’re bringing it down. I bought in and it really has shown. I think that’s a big, big thing for my success — is buying in, experimenting with it, switching a few things, and then going from there.”

Zeferjahn is currently regarded by SoxProspects.com as the No. 31 prospect in Boston’s farm system, which ranks 14th among pitchers in the organization. He operates with a three-pitch mix that consists of a 97-98 mph four-seam fastball that has reached triple digits this year, an 84-88 mph sweeper, and a cutter that “plays like a slider.”

As it stands now, Zeferjahn is just one call away from reaching the major-leagues. With that being said, the hard-throwing righty can also become eligible for the Rule 5 Draft this winter, so this promotion to Worcester should help in determining if he is worthy of a spot on the Red Sox’ 40-man roster before the year is over.