Jonathan Papelbon is digging in.

"I like when people doubt me," the Red Sox closer said prior to his team's series-ending loss to the White Sox on Thursday night at U.S. Cellular Field.

The comment was born out of remembering those who believed he wouldn't hold up as a reliever, and would be better served remaining a starter heading into the 2007 season. ("A lot of people called me crazy," he noted.)

But it also was clearly in response to those offering opinions regarding Papelbon's downturn this season. As has been well-documented, the closer has never had the kind of struggles he endured this year, which has translated into career highs in ERA (4.02) and blown saves (8).

"Obviously, I wish I had a better year than I did this year. I think there was a domino effect this year. I think there were a lot players on this team that wished they had better years, but when you have players hurt there is going to be a domino effect. But I'm healthy, and that's the key," Papelbon said.

"The season is more satisfying to me [than frustrating], because of one simple thing: I'm throwing this breaking ball, the slider, that is better than I've ever thrown. In my mind, now I'm going into a healthy, to-be-free agent year with three pitches and healthy. I've reached exactly where I want to be with health, where I want to be as a pitcher, and I can't complain."

In Papelbon's eyes, the excitement of what awaits pushes aside any recent struggles.

As he points out, his velocity has been as good as it has been in the past few years,  his health is fine, and in the past few weeks the closer has discovered a slider that has nurtured a new wave of optimism.

He acknowledges his 2010 campaign wasn't like his previous five in the big leagues: "I would say my focus was a little off this year. I wavered a little bit. My mental game was a little bit off because I wavered more than I did in the past. On the field, off the field, everything." But it was a diversion that hasn't left Papelbon lacking confidence heading into the final year before becoming eligible for free agency.

"I think everything has come full circle," the 29-year-old said. "I've developed a third out-pitch, which I've been really successful with this year, and it's only going to get better. How may closers out there have three legitimate out-pitches? I think for me, and my career, and my health, everything has come full circle to this final year. I'm looking forward to a big year next year, with a lot of motivation.

"I'm definitely very happy the way my career is going. I wish I could have had a better year this year, but it's all hindsight and it all comes full circle to now, using my slider and everything else.

"My pitches are there, my health is there, my velocity is there. What else can I hope for?" 

For Papelbon, the answer isn't hard to find.

Back in '07, fresh off the decision to serve as the Red Sox closer, Papelbon spoke of his intention to go year-to-year with his contract if a suitable multiyear deal didn't present itself. In the pitcher's mind, it hasn't. For two straight years he has settled on record-breaking deals, allowing him to avoid arbitration. (He made $9.35 million in '10, the richest contract for any second-year arbitration-eligible reliever.)

Now Papelbon is facing the last piece of his puzzle: One final season — armed with his aforementioned arsenal — before delving into the free agent experience he started eyeing years before.

He has talked time and time again about attempting to set the market for closers, just like Mariano Rivera did when he signed a three-year, $45 million deal prior to the '08 season.

"There's no question," Papelbon said when asked if he will be more motivated than ever in the coming months. "This offseason will be different than any other offseason, for sure, as far as motivation and what I need to accomplish. At the same time, I have a chance to do what no closer has done before and something for this role that can benefit the game. Just like Mariano did. I think there's a certain obligation for people out there at their position to try and better the game."

He is keenly aware of what Rivera is making, as well as the contracts recently doled out to closers over the past few seasons. Papelbon is first and foremost worrying about his own lot in life (remember, health, slider, velocity, etc.), but he isn't blind to what industry movement is paving his road to beyond next season.

"I think it's changed a little bit for the better. Closers are starting to get recognized a lot more," Papelbon explained. "I think it's definitely a role that will never get fully recognized.

"You know what we are? We're an insurance policy for your starters. And with insurance policies you have to pay the premium for the insurance policy."

How much that premium costs remains to be seen. It will undoubtedly depend on if Papelbon's current optimism can translate into the kind of season he fully believes is around the corner.

"I love a challenge," the reliever said.

Good thing. He's about to get perhaps his biggest one yet.