He feels this despite that wide-open sign that remains for the closer's role in manager Terry Francona's bullpen.
"This is a decision that Theo and I made at the end of last year so that Theo could have a plan going into Spring Training what kind of direction he wanted to take with the team," said Papelbon. "I think that was just a decision we made early, and that was the route he wanted to go."
Health was the primary reason for the switch. Papelbon's right shoulder broke down on Sept. 1, and after a thorough medical study, the Red Sox determined that he'd be better off with a starter's workload.
"For me, it not only plays into what they drafted me as, which is a starter, but it allows me to go out there and give them everything I've got on one day and build my body up to go do it in another five days," said Papelbon.
Papelbon, who was groomed as a starter throughout his time in the Minor Leagues, is enjoying his program this winter.
"It's a lot different, a lot more disciplined," said Papelbon. "That's the No. 1 thing. I have a daily routine that I can go by. I have it all charted out to where I go with my trainer, Mike Reinold, and I know what I have to do day in and day out. That gives me discipline, and it gives me something to go by, a guideline. Since I've been sticking with that guideline, my arm has been stronger than ever."
The 26-year-old Papelbon got a reality check late last season, and it is one that will probably help him through the rest of his career.
"For me, my livelihood is my arm," said Papelbon. "I treat it like a little baby now."
Unfortunately for opposing hitters, Papelbon won't be doing much babying once he steps on that mound every fifth day.
"I'm not going to change the way I go after hitters," vowed Papelbon. "I'm still going to go right after them. I'll just be throwing a few more pitches."
Still, isn't it asking a lot to expect Papelbon to have the same kind of success that he did as a light-out closer? Not according to Papelbon.
"I went to a Celtics game [on Wednesday] night and was sitting courtside, and some guy came running onto the court and said, 'We have to get 20 wins out of you,'" said Papelbon. "I like it; I like the pressure. I expect myself to go out there and do the best that I can and be in that upper echelon. It's no different putting it on myself than the fans putting it on me."
Papelbon will be part of a power-packed rotation that also includes Curt Schilling, Josh Beckett, Daisuke Matsuzaka and knuckleballer Tim Wakefield.
"You go into Spring Training and you thrive on competition. It's fun," Papelbon said. "That's what Spring Training is all about. That's the nature of baseball."
What if the closer's derby winds up being a disaster and nobody emerges? Could Papelbon see himself returning to that role?
"It wouldn't surprise me a whole lot, but at the same time, we've got some good competition at that spot," said Papelbon. "There's no doubt it. The guys we have right now -- as far as [Craig] Hansen, [Manny] Delcarmen and [Joel] Pineiro -- the competition in the bullpen is going to be stiff. That's only going to make us better."
And, as far as Papelbon is concerned, both he and the Red Sox will be better with him taking the ball for 200 innings a season instead of 70.