NEW YORK -- Yankees manager Aaron Boone isn't certain that Clint Frazier will be able to play baseball again after the outfielder was pulled from a minor league rehab assignment Monday amid continuing issues with his vision.

"We'll see," Boone said when asked whether Frazier would play again. "Obviously, he's been through a lot and been through a lot of seeing a lot of people and a lot of testing and everything. We'll just try and continue to follow and support him where we can. But as of right now, a little holding pattern. I know he feels well today, so we'll just see."

Frazier, 26, began a minor league rehab assignment last Tuesday after missing nearly six weeks because of dizziness and other symptoms consistent with vertigo. He went 4-for-10 over three games, but Boone said Frazier felt unwell prior to Sunday's game with Double-A Somerset and took himself out of the lineup.

Frazier was formally pulled from the rehab assignment Monday and transferred to the 60-day injured list.

"Just didn't feel like he was good enough to post," Boone said before New York played the Los Angeles Angels on Monday. "And so, decided to pull the plug, and we applaud him for making that decision."

Frazier was placed on the injured list July 1 with what was initially called vertigo and later defined as a possible vision issue. He missed nearly all of the 2018 season with lingering concussion symptoms, but it's not clear whether his current concerns are related.

A 2013 first-round pick by Cleveland, Frazier hit well in 2019 but was banished to Triple-A for much of the season following several defensive miscues.

He finally cracked New York's crowded outfield for regular playing time in 2020 and shined. He batted .267 with a .905 OPS and steadier defense in left and right field, earning an everyday role for the 2021 season.

The breakout has fizzled this year. Frazier hit .186 with five homers and a .633 OPS in 66 games before going on the IL.

Also Monday, right-hander Luis Severino (right shoulder tightness) had an MRI as planned. Boone said the team hoped to review the results before the end of the night.

Catcher Gary Sanchez (COVID-19 IL) hit on the field and could be activated Tuesday for a doubleheader against the Boston Red Sox.