The Mariners recalled Kowar from Triple-A Tacoma and placed him on the 15-day injured list Wednesday with a right shoulder impingement, retroactive to Aug. 19.

Kowar was sent down to Triple-A in mid-August but hasn't pitched for Tacoma since being demoted. Now dealing with a shoulder issue, the 28-year-old will return to the big-league club to rehab his injury. He'll be eligible to return from the IL as soon as he's healthy, but there's currently no telling how close he is to activation.

Young is not in the Mariners' starting lineup against the Rays on Wednesday.

Young will be on the bench for beginning of Wednesday's game while Jorge Polanco shifts to the keystone, Cal Raleigh serves as the designated hitter and Mitch Garver gets the start behind home plate. Young struggled at the plate in August and has gone 1-for-25 over his last 10 games, which has lowered his season OPS to .639 across 240 plate appearances.

Estrada (quadriceps) was activated from the 7-day injured list at Double-A Chesapeake on Tuesday.

He missed a little under two weeks with a quad injury and went 2-for-3 with a walk and a strikeout in his first game back. Estrada, who was promoted from High-A Aberdeen to Chesapeake on July 29, is slashing .310/.372/.563 with five home runs, four steals and a 14.1 percent strikeout rate in 19 games for the Baysox. The 20-year-old switch hitter has split time between second base and left field since getting to Double-A.

Fitts (arm) was diagnosed Tuesday with inflammation in his brachial plexus following an MRI, Tim Healey of The Boston Globe reports.

According to Healey, the brachial plexus, is a bundle of nerves that begin in the spinal cord and extend through his shoulder and arm, and the finding from Fitts' MRI weren't anything unexpected. The Red Sox aren't yet putting a timeline on Fitts' return, as the team will wait and see how he responds to rest and treatment before clearing him to start throwing again.

Red Sox manager Alex Cora said that Tolle will start Friday's game against the Diamondbacks in Arizona, Gabrielle Starr of the Boston Herald reports.

Tolle would have been available to take the hill Wednesday against the Guardians on four days' rest, but because he's received at least five days of rest ahead of every appearance this season, the Red Sox weren't yet ready to deviate from that plan. Cora said that the Red Sox envision Tolle continuing to start games in September, so it looks like he'll be a regular part of the rotation moving forward after turning in a promising MLB debut this past Friday against the Pirates. In that outing, Tolle punched out eight batters and induced 14 swinging strikes on 84 pitches while limiting the Pirates to two earned runs on three hits and two walks over 5.1 innings.

May will work in relief behind opening pitcher Brennan Bernardino for Wednesday's game against the Guardians, though manager Alex Cora said that the right-handed May will be available for up to 40 pitches, Tim Healey of The Boston Globe reports.

Since May will be pitching on three days' rest after most recently starting in last Saturday's 10-3 loss to the Pirates, he'll face a tighter restriction than if he were operating as bulk reliever on normal rest. Cora noted that the Red Sox aren't yet preparing for May to move to the bullpen on a permanent basis, as the 27-year-old is still likely to make a start during next week's series versus the Athletics. Since being acquired from the Dodgers at the trade deadline, May has produced a 5.68 ERA, 1.70 WHIP and 25:11 K:BB in 25.1 innings through his first five outings with the Red Sox.

Triple-A Worcester manager Chad Tracy said Wednesday that Harrison is tending to an ankle injury, and the southpaw is without a clear timeline to resume pitching, Katie Morrison-O'Day of MassLive.com reports.

The southpaw had recently joined the Red Sox in Boston and appeared to be in consideration for a start Wednesday against the Guardians, but the big club will ultimately have lefty Brennan Bernardino serve as an opener in front of bulk reliever Dustin May in that contest. Harrison's ankle injury may have played a part in him being bypassed for the start with Boston, and it's yet to be determined whether the issue will result in him landing on Worcester's injured list.

Narvaez is not in the Red Sox's starting lineup against the Guardians on Wednesday.

Narvaez will be on the bench for Wednesday's series finale after going 2-for-4 with a double during Boston's 11-7 win over Cleveland on Tuesday. Connor Wong will start behind the dish and bat ninth.

Lowe is out of the lineup for Wednesday's game against the Guardians.

The left-handed-hitting Lowe was included in the lineup against Cleveland southpaw Parker Messick in Monday's 6-4 win, but he'll hit the bench while the Guardians send another lefty (Joey Cantillo) to the bump for the finale. Romy Gonzalez will check in for Lowe at first base.

Santander (shoulder) will continue his workout program with the Blue Jays this weekend in New York and could begin a rehab assignment Tuesday with Triple-A Buffalo, Arden Zwelling of Sportsnet.ca reports.

The veteran outfielder has been sidelined over three months while recovering from a dislocated shoulder, but he's in the final stages of his rehab program. Santander will need at least five games in the minors to get back up to speed, which means that the earliest he'll be able to rejoin the Blue Jays will be Sept. 14 versus the Orioles.