The 33-year-old closer is a lot of things - a former All-Star, the recipient of the richest contract for a reliever in big-league history, an important piece of the Phillies' roster - but he is almost always loud.
And it was that defining characteristic that put Papelbon in a bad spot last summer, when the Phillies were in the midst of their worst stretch of the season.
"I definitely didn't come here for this," Papelbon told MLB.com after the Phillies ran a losing streak to eight games in Detroit last July.
Less than 2 weeks later, Papelbon was pointing fingers, but not naming names, for what he believed was a lack of fundamentals by a teammate that helped him blow a save. None of Papelbon's comments was well-received inside Citizens Bank Park, nor among Phillies fans.
It didn't help the closer's case that his comments came during a 6-week period when he had nearly as many blown saves (six) as saves (seven).
"He had regrets about what he said," Phillies manager Ryne Sandberg said. "I think in some regards, from the input that I got back . . . he really wasn't sure what he said. I know the guy wants to win, I know he looks good in camp, I know that he's taken on a leadership role within his group . . . This is still his team."
The Phillies tried (and failed) to trade the closer this offseason. But he's midway through his 4-year, $50 million contract, still on the team, and vowing to leave the negativity in the past.
"This year, I'm definitely trying to be a lot more of a positive influence and be more upbeat," Papelbon said.
Does that mean he's admitting he wasn't a positive influence in previous seasons?
"I'm just speaking for myself and nobody else," Papelbon answered during a 20-minute session with reporters yesterday afternoon just inside the leftfield foul line at Bright House Field. "At times, when you lose [eight] games in a row and you're in Detroit and you say you didn't come here for this, that gets [spun] in a couple of directions. For me, I didn't come here to lose. I came here to win. I came here to win a world championship. I don't take losing very well.
"The one thing I can say that does upset me is a lot of you [media] guys here - not pointing anyone out - took that as I'm a bad teammate, which is definitely not true. I'd break my back for my teammates. I'd do anything. They're my brothers. I'm with them more than my family. If you could ask all 25 guys in there, I live and die for my teammates."
If there are any lingering issues from last year, Sandberg said they will be addressed. The manager, who took over for Charlie Manuel in the middle of August, is a firm believer in communication, and said if he has to talk to a player every day about something, he'll talk to a player every day.
Papelbon said it won't be a problem this year.
"All I'm trying to do is just feed off of our manager, Ryno, and take this energy and positivity and go into the season and see where it takes us," Papelbon said. "Anybody can sit here and say we've sucked the last 2 years and we've haven't made the playoffs and we've been damn near last in our division every year - no, I didn't come here for this, but I didn't come here to be negative and let that get the best of me . . . The last 2 years, I might have let that get the best of me."
Papelbon also said he didn't plan to filter his comments, either. "Maybe I forgot to put the coffee filter in," he said.
Regardless if Papelbon talks a good game, the Phillies certainly need him to pitch more than a few if they hope to contend in 2014. In 2013, Papelbon's numbers weren't All-Star worthy.
He converted 29 of 36 save attempts for a 80.6 percent rate, which ranked 29th out of the 32 MLB closers with at least 20 save chances. He also allowed a career-high 59 hits in 61 2/3 innings last year, the fewest innings he's pitched in a season since 2007.
Perhaps more concerning is the steady drop of Papelbon's fastball velocity since arriving in Philadelphia.
According to PITCHf/x data, utilized in every big-league ballpark, Papelbon's average fastball clocked in at 95 mph in 2011, his last year with Boston. In 2012, his average fastball was 93.8 mph; last year, it was career-low 92 mph.
Perhaps it's not surprising, then, that Papelbon's strikeout rate (strikeouts per nine innings) has gone from 12.17 to 11.83 to 8.32 in the same time frame. His 8.32 strikeout rate last season was a career low.
Papelbon said the decline could be a product of pitching for a losing team. The closer position, he said, is an "intensity-driven role" and the Phillies lacked games with that atmosphere in 2013.
"On nights when the ballpark is full and it's a close game and we're in a race - that's what makes me tick," Papelbon said. "That's the big reason I decided to be a closer . . . when the dial is turned up and there is something on the line, I just seem to be at my best. When it's a day game in New York and you're 12 games behind, that dial ain't really turned up . . . that ain't really how I go. I'm sure velocity has something to do with that."
Papelbon also said he wasn't always feeling 100 percent, but said it was nothing more than "nagging stuff."
He is healthy now. He is also ready to contribute and forget about the negativity he helped cultivate in the clubhouse last year.
"I'm not going to come back and apologize for something I said if it is something that I feel," he said. "I just don't live my life that way. If I say something, it's because I mean it and I'll become fiery and emotional. That's who I am. If I say the wrong thing, then so be it. As long as I'm fighting for my teammates and going to war for them and doing everything I can to help my teammates win a ballgame, nothing else will matter."
On Twitter: @ryanlawrence21