The Twins announced the switch on Monday for the 30-year-old Mauer, who missed the last six weeks of the schedule recovering from his head injury. He took a foul tip off the mask on Aug. 19. During a conference call with reporters, Mauer said he's feeling fine and symptom-free, having begun his offseason workouts.
The sensitivity to light and noise, irritable moods and headaches lingered into October, however, prompting him to seek medical advice from Mayo Clinic doctors and team physicians about the prospect of continuing to play behind the plate.
"When I kept gathering information, to be honest with you, it wasn't really even a decision," said Mauer, who is signed through 2018 with $115 million remaining on his contract. "I kept searching to see if it was going to be OK, if it was going to be safe for me to go back there and catch, and I just wasn't finding that."
He added: "All it could take is one foul tip in pitcher's batting practice, and I'm out for two or three months or even more."
Twins general manager Terry Ryan said the organization would've supported whatever Mauer decided was best, even if he felt he could keep playing the position with the most inherent injury risk of anywhere on the field.
"I'm happy that he's chosen to make the transition, but had he decided that he wanted to catch I'm not sure that anybody was going to stand in his way," Ryan said.
Ryan, who traded Mauer's close friend, first baseman Justin Morneau, a couple of weeks after Mauer was hurt, acknowledged this move makes the potential pursuit of Morneau in free agency improbable.
Mauer won the Silver Slugger award for American League catchers this year after batting .324 with 11 home runs and 47 RBIs in 113 games. Taken by the Twins, his hometown team, with the first pick in the 2001 draft and given the job as a 20-year-old to start the 2004 season, Mauer has been the catcher in 920 games.
"I really enjoy going out there and competing, and I'm thankful still be able to do that. ... But it's frustrating it had to end sooner than I anticipated," he said.
Mauer has three Gold Gloves, three batting titles, six All-Star game selections and the 2009 AL MVP award as a catcher. Can he amass similar accolades at a position crowded with top hitters is to be seen. As for the effect on the value of his $23 million annual salary, his rotisserie league worth or his Hall of Fame credentials, well, Mauer predictably said he's not worried about any of that.
First there's his family, including wife Maddie and twin infant girls Emily and Maren. Then there's the Twins, who are better off with a healthy Mauer at first base than with an injured Mauer at catcher. The men behind the mask took quite a beating around the majors this season, with Detroit's Alex Avila, Oakland's John Jaso and Kansas City's Salvador Perez all missing time due to concussions.
"I had one when I was younger, but I probably had several that went undiagnosed. You're just kind of wired to play through it," Mauer said.
Mauer said he sustained "two significant blows" to his head that mid-August afternoon, a makeup game against the New York Mets from April rendered meaningless with both teams buried in the playoff race. With problems with his back and legs behind him, Mauer had been feeling as fit and strong as ever the last two years.
"We wouldn't be having this conversation if I didn't have that concussion," he said.
Former Twins catcher A.J. Pierzynski is among the veteran free agents available this winter, but Ryan said his priority is starting pitching. Josmil Pinto showed some potential after Mauer was out, and Ryan Doumit has plenty of experience. Other options are Chris Herrmann and Eric Fryer.
Mauer has played 56 games at first base in his career, committing four errors in 536 chances for a sparkling .993 fielding percentage. The natural athleticism that made him a standout point guard and quarterback in high school serves him well anywhere on the baseball field, and he ought to be able to pick up defensively where Morneau left off.
Where Mauer can't match Morneau is with raw power, long widely considered the most important asset at first base, but Mauer has a career .873 on-base-plus-slugging percentage, 20th among all active players regardless of position.
With increased availability and fresher legs, he could easily recalibrate his annual average of roughly 10 home runs. Mauer spoke with Morneau shortly before he addressed the media.
"He was a catcher way back in the day, and he said, 'You're going to be amazed at how much better you feel,'" Mauer said. "I'm looking forward to that."