Red Sox likely to place John Schreiber on injured list with right lat tightness

Red Sox reliever John Schreiber is likely going to be placed on the injured list after leaving Monday night’s 10-1 loss to the Mariners at Fenway Park with right lat tightness, according to manager Alex Cora.

Schreiber came on in the seventh inning and struck out the first batter he faced in Ty France. The right-hander then delivered a 2-1, 93.3 mph sinker to Julio Rodriguez and could immediately be seen flexing his throwing arm on the mound.

That prompted Cora and head athletic trainer Brandon Henry to emerge from the Red Sox dugout. After a lengthy conference on the mound, Schreiber left the field with Henry and was replaced by lefty Richard Bleier.

When speaking with reporters following Monday’s blowout loss, Schreiber indicated to reporters (including MassLive.com’s Chris Cotillo) that he had been dealing with discomfort in the area of his lat (the latissimus dorsi muscle) on his right side over the last few days and reaggravated it on his final pitch to Rodriguez.

“It has been tight a little bit this past week,” explained Schreiber. “I was throwing some bullpens, it was coming out good. It felt like something I could get through… Tonight, it was coming out really good, I thought. That last pitch, maybe a little bit too much extension there, and it tightened up.”

Including Monday’s outing, Schreiber now owns a 2.12 ERA and 1.29 WHIP with 21 strikeouts to eight walks in 18 relief appearances (17 innings) for Boston this season. Though the Red Sox are optimistic that the 29-year-old’s stint on the injured list will only last the minimum 15 days, the structure of the bullpen will change in his absence.

As noted by Cotillo, this will be Schreiber’s first injured list stint as a major-leaguer. The righty is slated to undergo further testing on Tuesday and that will likely provide a more concrete timeline for his recovery.

“I’m frustrated, obviously, that I’m not going to be able to compete for, I don’t know how long,” Schreiber said. “We’re going to evaluate tomorrow. Hopefully, some really good results. We’ll see what happens.”

Schreiber is not the only reliever the Red Sox will be replacing on Tuesday. Left-hander Brennan Bernardino was also optioned to Triple-A Worcester after allowing one run over 1 1/3 innings of relief on Monday night.

It is not yet known who will be taking the place of Schreiber and Bernardino on the big-league roster. Potential candidates include Justin Garza and Kaleb Ort, who are both on the 40-man roster, as well as Jake Faria, Oddanier Mosqueda, Andrew Politi, and Ryan Sheriff, who are not on the 40-man roster.

With that being said, the Red Sox have an opening on their 40-man roster after designating Ryan Brasier for assignment on Monday. It is also worth mentioning that Kutter Crawford — who has been sidelined by a left hamstring strain since May 4 — is expected to come off the injured list on Friday.