"Catching is such a grind," Napoli said. "People don't really understand what it's like to be back there and trying to hit when you're tired and you have no legs."
How much longer might Napoli play due to the position switch?
"I mean, a lot," Napoli said. "Physically, [catching] takes it out of you. Your legs, your knees, just your whole body. Foul tips all the time. I'm hoping it puts a couple extra years on there for me."
Napoli is 32 years old and should be able to hit prodigious home runs for years to come without the toll of catching.
And catchers, particularly the ones who are major offensive weapons, could start to make the move to another position earlier in the coming years.
Minnesota's Joe Mauer, who played against Napoli and the Red Sox in Boston's 4-3 victory Thursday -- during which Napoli nearly had his third spring home run on a reviewed foul ball -- is the latest to make the switch.
"I'm pretty sure you'll see [Buster] Posey do it soon," Napoli said. "Especially guys who have contracts like that. Sure, they can do special things behind the plate, but some of those guys can hit, too."
Last year, his first as a full-time first baseman, Napoli also proved he could field. Some of the metrics demonstrated that he should have been one of the finalists for the American League's Gold Glove Award.
"I knew I'd work at it to try to be good over there," Napoli said. "I think I'm a little more athletic than people thought."
Napoli seems to miss the mental aspect of catching more than the physical parts.
"I definitely don't miss the physical part of catching, so it's just different in the sense of, I wasn't in every play anymore," Napoli said. "It was weird at first. Sometimes I'd go two or three games without even getting a ground ball. It's a little different, but I like where I'm playing now."
Though his defensive prowess has been welcomed, Napoli is most valuable because of his bat.
Last year, despite an extended midsummer slump, Napoli belted 23 homers and drove in 92 runs to go along with a solid slash line of .259/.360/.482.
And for the second time in three years, Napoli made a name for himself in the most important month of all -- October.
He hit what proved to be the game-winning homer against Justin Verlander in a 1-0 victory in Game 3 of the AL Championship Series, and then a mammoth blast two nights later against Anibal Sanchez that helped win Game 5. In Game 1 of the World Series, it was Napoli's three-run double into the gap that got the Red Sox off and running.
But there's a chance his second season could be even more fruitful. The hip questions that dogged Napoli at this time last year and forced the restructuring of his contract are all gone.
"That's freed him up mentally," said Red Sox manager John Farrell. "It's also freed him up physically, because he's been able to have an offseason that was normal. His workouts have been regular. I see Nap now with more freedom in his swing to where he's pulling the ball a bit more regularly. That's not to say he's changing his style. He's just more freed up to address pitches on the inside part of the plate more regularly. Hopefully it translates to bigger numbers. He's in a good place right now."
Though a slump at some point this summer is probably inevitable for Napoli, a notorious streak hitter, he hopes to get out of it sooner. And there is sure to be less panic among the masses of Red Sox Nation.
"It's just what it is. I go through those periods," Napoli said. "That's how my whole career has been. I just never give up. I'm still giving an effort and working even when I'm not hitting. Just keep grinding. Hopefully I'll come out of it sooner rather than later. That's just part of baseball. You just try to minimize it. I go through some long slumps, but when I get hot, I get hot."
As far as the ring Napoli will receive on April 4 at Fenway Park, it only makes him hungrier for another one.
"I want to do it again," Napoli said. "I'm not just satisfied with it. Once you taste it, that's all you want. Not that you didn't want it before, but you actually know what it's like. I'm motivated. It's time to defend it. It's our title now, so someone has to take that away from us."