Mauer's return to the lineup hit another roadblock while working out Thursday before Minnesota's game against Cleveland, when continued sensitivity to light and noise while jogging around and fielding ground balls forced him to back off.
"We kind of got a better feel for where I'm at, and I'm not there yet," Mauer said.
The 35-year-old Mauer has also been dealing with a cervical strain resulting from a May 11 dive for a foul ball. He played for another week before departing midgame May 18 and being placed on the disabled list the following day.
Mauer said he has been told by the team's medical staff that some recurrence of symptoms is to be expected, but that didn't stem his disappointment. He planned to stay at the ballpark and watch the game from the dugout, another test of sorts of his ability to withstand the typical sensory bombardment over the course of a game.
Batting practice hasn't been a problem, but there's been no discussion of a soft return as a designated hitter.
"When I come back, I want to stay," he said. "I don't want to go back."
Mauer revealed Thursday that he felt the symptoms "pour on" during his drive home after the May 18 game from which he was removed early. He stayed home that weekend to rest, and progress has been slow since. A previous concussion altered Mauer's career in 2013 and forced his move from catcher to first base. His comfort at the plate didn't come back in the form of reliable production until last season.
"We've obviously seen improvement, and some of those things have subsided," manager Paul Molitor said. "But there's still an adaptive period here where he's getting accustomed to what it takes to play in a major league game."
Mauer is batting .283 with a .404 on-base percentage. Logan Morrison has mostly been playing first base in his absence. The Twins have been ravaged by injuries this year, with center fielder Byron Buxton going back to the disabled list Wednesday because of a broken toe that hasn't healed. Another round of X-rays revealed no additional damage, just the same fracture.
"I tolerated it as much as I could," said Buxton, who has just four extra-base hits in 90 at-bats. "It comes to that point where you feel like you're not helping the team out, so you've got to give it up to that next person and just root us on."