On Sept. 26, 2011, Joe Mauer trudged into the Twins clubhouse with sleepy eyes and a strained voice. Diagnosed with pneumonia two weeks earlier at the Mayo Clinic, the three-time American League batting champion was a shell of himself, still down at least 15 pounds from an early-season viral infection.

Mauer had finished the first year of his eight-year, $184 million contract batting .287 with three homers and 30 RBI in 82 games.

There had been summer-long skepticism from media and fans commenting on talk radio and online message boards about the main issue that had derailed his season, an injury the Twins called "bilateral leg weakness." Was there something more? Pausing several times to cough, Mauer insisted he wasn't suffering from anything more serious.

"The fact is, I have pneumonia," he said. "I'm not over it yet. That's first on my list to take care of. Hopefully I can get strong and get ready for next year."

Looking back, it's easy to understand why people doubted him. But he did get healthy, and he did get stronger, and 12 months later Mauer is a premier player again.

Besides challenging for his fourth batting title at .320, Mauer leads the majors in on-base percentage (.414), and if he remains in the lineup through Wednesday's season finale, he will reach 147 games played, one more than his career high of 146 set in 2008.

"Coming into the year, that [playing more] was my No. 1 goal," Mauer said. "I've always said, 'If I'm on the field, things will take care of themselves.' "

In June, Mauer missed four games because of a strained thumb and three games because of a sore hamstring. In mid-September, he missed five games because of back spasms. But he avoided the disabled list, and no, it wasn't just an effort to quiet his critics.

"I don't think I need any more motivation from anybody," he said. "I'm a very determined person. This is what I love to do, and I know I only get one shot at it, really.

"I've always said I want to be the best player I can be. I'm doing everything in my power to be that type of player, and I don't need anybody else's opinion on it really."

Hall of Famer Paul Molitor, a fellow Cretin-Derham Hall product, dealt with criticism with the Milwaukee Brewers when injuries limited him to fewer than 120 games in five of his first 10 seasons. Molitor hasn't spoken to Mauer about this but said it was nice to prove he could stay healthy over the second half of his career.

"It's hard when you're up in the training room, watching on TV and the opposing announcer is talking about you," Molitor said. "It's not so much hearing that you're injury-prone, it's when they start talking about your integrity or question your decisions on whether to play or not to play.

"It does motivate you, and it gives you some satisfaction when you prove them wrong."

Mauer, 29, spent his down time searching for solutions. He and Twins strength and conditioning coach Perry Castellano attended a training seminar in Bradenton, Fla. Mauer remodeled the workout facilities at his home in Fort Myers, Fla., giving him the exact equipment he uses at Target Field.

Because of the pneumonia, he couldn't resume training until Thanksgiving. But by TwinsFest in late January, he was back to his playing usual weight of about 230 pounds and feeling strong.

Manager Ron Gardenhire made sure he stayed that way, keeping Mauer in the lineup throughout the season but catching him less. The Twins signed Ryan Doumit, giving them a backup catcher who is batting .277 with 18 home runs.

Mauer has 71 starts at catcher, 38 at first base and 31 as the DH. Is this a formula the Twins can use moving forward, with about half of Mauer's starts coming at catcher? Gardenhire said that will depend on next year's personnel, but the Twins already have given Doumit a two-year extension.

"All I know is we need [Mauer] on the field, and this year's worked out pretty good," Gardenhire said.

Some fans aren't satisfied, and there was a smattering of boos directed toward Mauer, especially early in the season. Mauer hit 28 home runs during his 2009 MVP season, right before signing his extension. But in his other six full seasons, Mauer has averaged 9.5 homers. This season, he has 10.

"No one has ever said that we thought Joe Mauer was going to hit 28 home runs every year, especially with the move from the Dome to [Target Field]," Ryan said this summer. "He made the All-Star team. He's been in the lineup for the most part. So if [people have] a criticism, it's only because of the dollars."

In a lost season, Ryan and Gardenhire appreciate having Mauer's batting title chase as a late-year story line.

"I think we all take it for granted because he makes it look so easy," Gardenhire said. "Three hits here, two hits there -- it's a constant for him. It's incredible watching him."

Mauer wants to finish strong, and he's looking forward to a "normal offseason." He will go in healthy for the first time since 2009. In December 2010, he had arthroscopic knee surgery, and rushing back caused most of his 2011 problems.

There will be one wrinkle this offseason, but it's a good one. Mauer and his fiancée, Maddie Bisanz, are planning a fall wedding, though he's mum on the details.

"I don't even know," he said. "I'm in on some of the things that are happening, but she's been real good, letting me focus on the season. She gets it. She understands what my year is like. It's a hectic time, and it's an exciting time for both us. We have a lot of good things to look forward to."

The Twins can look toward Mauer's 2013 season with similar optimism.