One Under-The-Radar Reliever For Red Sox To Sign

Since Craig Breslow took over as the Boston Red Sox’s Chief Baseball Officer, he has targeted specific traits in relief pitchers. Among those traits are fastball velocity and extension towards home plate.

Aroldis Chapman is the prime example of these traits. He throws as hard as anyone, while striding down the mound 7.3 feet, among the furthest in baseball. He’s not the only hard thrower Breslow has acquired. Jorge Alcala, Jordan Hicks and Justin Slaten all throw hard. Liam Hendriks, Luis Garcia and Jovani Moran all exhibit plus extension as well.

While the industry believes the Red Sox adding a high-end reliever isn’t a priority, additional bullpen depth is never a bad thing. Former All-Star reliever Alexis Diaz exhibits characteristics Boston has targeted, and he has connections to Boston.

According to Francys Romero, Diaz is spending the winter working out with Hector Berrios, the same coach who trains Chapman in the offseason. Diaz has struggled over the past two seasons, but is only 29 years old and posted a 1.84 ERA in 2022 and a 3.07 ERA in 2023.

In 2025, Diaz spent time with the Cincinnati Reds, Los Angeles Dodgers and Atlanta Braves. He posted an 8.15 ERA over 17 2/3 innings. He’s always struggled with control, but walked a career-high 14.1% of hitters last season.

What might make him attractive to the Red Sox is his extension. He strides down the mound 7.6 feet, placing him in the 99th percentile. He typically sits at about 94 mph, but his extension makes it appear closer to 97 mph. The approach angle is also remarkably flat due to a low release height, making the pitch difficult to square up.

On top of that, at his best, Diaz featured a wipeout slider. In 2022 and 2023, the swinging strike rate against the pitch was over 20% and the chase rate was over 40%, helping him strike out more than 30% of the hitters he faced in that span. In the following two seasons, he threw the pitch in the zone more frequently, and he saw his swinging strikes decrease.

Diaz has his defects, but Breslow has a history of low-risk, high-reward moves in the bullpen. It won’t cost much to bring Diaz to Boston, and the upside is remarkable. The Red Sox were able to cut Aroldis Chapman’s walk rate by almost eight percent. If they can get Diaz in the zone, the dividends could be massive.