Red Sox’ bullpen gets thinner as Justin Slaten forced onto injured list – The Boston Globe

However, he experienced the soreness after an Aug. 9 appearance against the A’s, and again following an inning Aug. 12 against the Blue Jays. On Saturday, he started to loosen in the bullpen during the Sox’ 4-0 win over the Pirates, but immediately recognized that the discomfort had worsened.

“It just got a little too much to the point where I was pitching and just for two or three days afterward just not recovering well at all,” said Slaten. “It’s better for me, for the team, for the guys in the bullpen to just go ahead and get this cleaned up, get it fixed [with rest], and then be ready to go down the stretch.”

Slaten has a 4.60 ERA and 28 percent strikeout rate for the season, numbers inflated by early season struggles. Through the Sox’ hot stretch, he’d been a reliable contributor to the late-innings relay.

He hasn’t blown a lead since May 22, and was dominant during a recent 10-game stretch from July 7 through Aug. 2, logging 8⅔ scoreless innings with 10 strikeouts and one walk.

The righthander said he’ll meet with a doctor in Boston this week, and was unsure if he’d need an MRI. (His prior bouts of soreness haven’t required one.)

“We’re pretty confident that hopefully it won’t take too long,” said Slaten.

With both Slaten and Whitlock out, the significance of the Sox’ deadline trade for Erik Miller has grown. The lefthander has yet to allow an earned run and has recorded a 41 percent strikeout rate.

“This is why [the Sox traded for Miller],” said interim manager Chad Tracy. “Having him and looking down there, saying there’s still some viable options down there to get us through this, it’s very important.”

Aroldis Chapman’s scoreless appearance in a non-save situation Saturday night was worth $13 million. The outing marked his 40^th of the year, making a mutual option for the 2027 season guaranteed so long as the 38-year-old passes a year-end physical.

“I feel like home here,” Chapman said via translator. “I’m super happy that I’m able to come back next year to a place that I really like.”

The Sox likely share his enthusiasm. In two seasons in Boston, Chapman has a 1.50 ERA (lowest in team history by a pitcher with at least 100 innings) and 34 percent strikeout rate (third highest).

As expected, Masataka Yoshida landed on the injured list Sunday with a hamstring injury he incurred Saturday night. He’ll be examined in Boston this week, at which point more will be known about his recovery timeline.

The DH is hitting .274/.347/.399 this season, but had been a force (.326/.380/.512) in August, earning increasingly frequent appearances as the leadoff hitter.

With Yoshida and Slaten on the IL, the Sox recalled catcher/infielder Mickey Gasper and lefthander Raymond Burgos from the WooSox.

Gasper hit .243/.305/.308 in 34 games while getting regular playing time in May and June. He’s posting a .337/.450/.566 line in Triple-A.

Burgos, who contributed six bullpen-saving innings across two appearances on back-to-back days for the Red Sox earlier this month, did it again Sunday. He pitched four innings of one-run relief around a 2-hour, 34-minute rain delay.

First baseman Willson Contreras received a day off to rest his left hamstring, an issue the Sox have been and will continue to manage carefully.

“He keeps us posted on if he feels like that’s getting a little tight,” said Tracy. “He’s getting a day to make sure we can get him healthy and on the field.”

Shortstop Trevor Story, out since mid-May with a sports hernia, kicked off his rehab assignment by going 1 for 2 and playing four innings at shortstop for Triple-A Worcester . . . In the middle of a stretch of games on 16 straight days, Alec Gamboa will start Monday against the Diamondbacks, with Brayan Bello available behind him. The decision to employ a bullpen game was made not only to give a fifth day of rest to Ranger Suarez (starting Tuesday) and Payton Tolle (Wednesday), but particularly to afford multiple extra days of rest to rookie Jake Bennett, who won’t pitch until the Giants series next weekend.

Alex Speier can be reached at alex.speier@globe.com. Follow him @alexspeier.