Kiermaier, a Gold Glove-caliber outfielder, hasn't played since July 9. He is hitting .228 with 7 homers, 22 RBIs and 6 stolen bases in 63 games this year.
"Yeah, it is [tough to grasp]," Kiermaier said. "It hasn't really hit me just yet. ... For right now I'm kind of in that limbo, in-between period, but I think we will all know more here shortly."
The earliest he could return from the IL is September. The 32-year-old is scheduled to see a specialist in Nashville after the All-Star break. A surgical procedure hasn't been ruled out.
"Just got to keep everything under wraps until a decision is made, and then we'll go from there," Kiermaier said.
The move with Kiermaier cleared a roster spot for second baseman Brandon Lowe, who was reinstated from the 60-day IL after being out since mid-May with a lower-back injury,
"I'm not going to be back anytime soon, so this was the move that needed to be made, and I totally understand, agree with it " Kiermaier said.
Lowe, who had 39 homers and 99 RBIs last year, hit .212 with five homers and 12 RBIs in 32 games this year before going on the IL.
"Immediately it just feels like a thicker lineup," Rays manager Kevin Cash said. "Brandon has been a force with a bat in his hand in our division for a couple years. We know what he's capable of when he's right at the plate."
Tampa Bay recalled left-hander Ryan Yarbrough from Triple-A Durham to start Saturday's game against the Baltimore Orioles. Reliever Ralph Garza Jr. and infielder Jonathan Aranda were optioned to Durham.
Starting pitcher Yonny Chirinos allowed one hit over a scoreless inning in his first game with the rookie-level Florida Complex League Rays against the FCL Braves. The right-hander, coming back from Tommy John surgery, last pitched in the majors on Aug. 16, 2020.
To make room on the 40-man roster, right-hander Shane Baz, out with a sprained right elbow, was moved to the 60-day injured list. Baz has been on the IL since July 13, meaning he can't be activated until mid-September.
Despite having the major's second-highest total of 15 players on the IL, the Rays hold the top AL wild-card spot. The list of injured players includes shortstop Wander Franco (right hamate bone surgery) and 11 pitchers, including ace Tyler Glasnow (Tommy John surgery in August 2021).