Analyzing the candidates for the last bullpen spot down the stretch

  

    All in all, the Red Sox bullpen has performed well above expectations this season. Anchored by offseason acquisition Aroldis Chapman turning back the clock a decade or so, the Sox have gotten good performance from a number of relievers, with Garrett Whitlock, Greg Weissert, Justin Wilson, and Steven Matz all performing well. Despite this, the Red Sox bullpen has seemed rather top heavy at times. While there is reason for optimism, such as the imminent return of Justin Slaten and the hope Jordan Hicks can find something, too many times has the Red Sox bullpen depth cost them games. A prime example comes in the form of Saturdays 7-5 win over Miami. With a 5 run lead in the 9th, Isiah Campbell could only record 2 outs while allowing 3 runs and forcing Cora to turn to Chapman with the tying run at the plate. This led to Chapman being unavailable to pitch in Sunday;s game, where the Red Sox blew a 3-2 lead in the 9th in a game they would lose 5-3. We've seen this happen before, most recently with Jorge Alcala, and, as Will Flemming says best, "that just cannot happen." So, as the Red Sox gear up for a September playoff push, here's my candidates for the final bullpen spot. 

Isaiah Campbell:

The aforementioned Campbell has struggled in limited action with the Sox, allowing 4 homeruns in just 14 innings of work. Despite these struggles, fangraphs data loves his stuff, grading his slider, sinker and curveball as above average offerings. Unfortunately, Campbell has been completely unable to put it together at the big league level, and hasn't fared all to well in AAA either, with a 4.17 ERA in 45 innings. It seems likely this could be Campbell's last chance with the Sox.

Jovanni Moran:

Moran was acquired this offseason from the Twins in exchange for Mickey Gasper after spending 2024 recovering from Tommy John surgery. Moran pitched very well in 2022 with the Twins, struggled in 2023 (despite a FIP a run and a half below his ERA), and underwent Tommy John before 2024. Moran made his Red Sox debut against the Astros on August 12th, striking out 2 and allowing 1 earned run in 2 innings of work. His fastball averages 93, but his low 80s slider has been his best pitch so far in his career. Moran's solid debut should earn him some more action. 

Zack Kelly:

Kelly was a key part of the Red Sox bullpen last year, but has failed to regain his spot after exiting a game in late June. In 56 innings last year, Kelly sported a 3.97 ERA with an above average K rate thanks in part to an amazing fastball-slider-changeup mix. All three pitches came back with stuff+ grades 10% better than league average, with his slider rocking a 134 stuff+. In 22 innings this season, Kelly has introduced a cutter and a sinker, giving him a 5 pitch mix where no pitch is being thrown over 30% of the time. Most of his underlying metrics suggest Kelly might be experiencing some bad luck, as his BABIP has skyrocketed to an unsustainable .344. Despite all this, Kelly's struggles have followed him to the minors, as he currently has an ERA north of 5 in his 21 AAA innings. 

Dustin May:

Despite the heavy price paid for the starter, it seems likely May would be the odd one out if the Red Sox decide to go to a 4 man rotation in October. May struggled in his first start, but had a bounce-back outing against a strong Houston team, throwing 6 scoreless while striking out 8. May showed improvement in velocity retention in this start, but his issues in his first start, where his fastball velocity dropped to 92-93 by his 60th pitch, linger. If May fails to build off this most recent start, don't be surprised if we see Cora start to use him as a high-leverage reliever, as his pure stuff on a one inning basis is still elite. 

Luis Guerrero:

Guerrero was a prime candidate to hold a high leverage roll this season after a strong showing last September, with some (me) predicting he could win the closer spot by June. Unfortunately, Guerrero struggled in 17 innings early, before hitting the 60 day IL in late June. Guerrero is eligible to return on August 28th, and is closing in on a rehab assignment. His fastball has looked much worse this season, with his velocity being a tick down across the board. The hope is that we can chalk that up to a bummy elbow, as Guerrero locked great in 9 games last September. 

Brennan Bernardino:

Bernardino has been a staple in the Sox pen for the better part of the last 3 seasons, but was recently demoted to AAA in favor of fellow lefty Chris Murphy. Bernardino was enjoying a strong campaign up to the point of demotion, and had in fact thrown 12 scoreless innings in July. Despite this, he was sent to Worcester at the beginning of August, where he has pitched 4 innings, striking out 8 while allowing 1 earned. It only seems like a matter of time before Bernardino returns to Boston. 

Chris Murphy: 

Murphy was initially chosen over Bernardino to remain in the Red Sox bullpen following the acquisition Steven Matz, but joined Bernardino in Worcester following an August 11th demotion. Murphy had been solid over 17 innings in June and July, but a pair of tough outings in San Diego, in which he walked 5 and recorded just 2 outs, spelled the end 27 year old. The hope is Murphy's feel for the zone will return, as he has held opposing batters to just a .162 BA this year in Boston.