He was an adrenaline junkie during his time in Boston from 2005 to 2011 and that's what made him one of the best in the game.
Whether it was running in from the bullpen with the Dropkick Murphys' "Shipping up to Boston" blaring and the Fenway fans on their feet and singing along, or the pure satisfaction he received from blowing a pitch past a helpless batter to earn one of his many saves, Papelbon was built to be a closer.
When he decided to leave Boston and sign with the Philadelphia Phillies as a free agent in 2012, he earned a massive payday with his four-year deal worth $50 million. After his departure, the Red Sox tried many options to replace his dominance but nothing worked out.
Koji-mania has hit the Hub.
Uehara has worked 24 consecutive scoreless innings over his past 21 outings. He becomes the third Red Sox pitcher to accomplish such a streak, joining Daniel Bard (25 innings in 2011) and Papelbon (21 in 2011). During his streak, Uehara has allowed only seven baserunners.
"Above and beyond what we've talked about with the consistency of strikes, I've come away from a lot of games in which he's closed out thinking almost that he has a sixth sense on the mound," Red Sox manager John Farrell said. "Which pitch to throw and which location, almost a feel for what the hitter at the time is looking for. The [Alexei] Ramirez strikeout was evidence of that today.
"He's very calm. Regardless of the role we've had him in this year, we've seen the consistency start to finish and he has saved our tail end all year long."
Uehara has retired the past 18 batters he's faced, including 17 during his past five outings. He hasn't allowed a baserunner in his past five save opportunities, which is the longest such streak by a Red Sox closer since Papelbon did it from Aug. 21 to Sept. 6, 2007.
Asked about Uehara's scoreless streak, David Ortiz said, "Let's talk about something else. I don't want no bad karma, let's keep it that way."
"He's a great pitcher," Red Sox catcher Jarrod Saltalamacchia said. "He throws a lot of strikes and keeps guys off balance. That split does three different things at times, so you can't really be ready for it. I've seen guys that look like they're pretty much sitting on it and it just does something different. He knows how to manipulate it and it's fun to catch."
There are many what-if scenarios in baseball, and watching Uehara enjoy this kind of success is another reminder that anything can happen in this game.
It had seemed almost inevitable that Bard would replace Papelbon once the veteran closer reached free agency and signed elsewhere. But that never happened. Instead, the Red Sox and Bard decided to convert the hard-throwing right-hander into a starter in 2012. The experiment failed and Bard never was able to regain the once-dominant control that made him one of the best setup men in the game between 2009 and 2011.
On Sunday morning, the Red Sox designated the once-promising power pitcher for assignment to make room on the 40-man roster for some new arrivals, including veteran infielder John McDonald and outfield speedster Quintin Berry.
The failed move to starter is easy to second-guess now that Bard hasn't been able to figure out his mental and physical issues, but had the Red Sox stuck with his natural progression to a closer, Bard could be closing games for the team.
He's not. Uehara is.
The Japanese import arrived in Boston as a free agent last December, not figuring to get a chance to close with the Red Sox. After all, the Sox had acquired All-Star closer Joel Hanrahan via trade from the Pittsburgh Pirates, and also were banking on Andrew Bailey, a former All-Star closer himself who was coming off an injury-plagued 2012.
In the winter, Farrell announced Hanrahan would be the club's closer and Bailey would be the setup guy.
But both landed on the disabled list with season-ending injuries earlier this season, which forced Farrell to look elsewhere for a closer. Uehara became the man.
He's not flashy on the mound, but his stuff is nasty.
"It isn't like the confidence is growing or anything like that," he said. "I know if I do my job, if I make my pitches I'll get the hitters out."
When Uehara enters the game, he always has a smile on his face, which is the opposite of Papelbon's glare. It's as though Uehara has a kill-them-with-kindness mentality.
"It's a very calm inning from our perspective," Farrell said. "Hopefully that run continues. Not only has he been efficient, but he's in complete control in the inning that he's out there, inning and a third, inning, whatever it might be, on back-to-back days. It's a very calming inning."
The Sox could be looking at more "calm" innings next season as well, as an option kicked in on Uehara's one-year deal that turned it into a two-year deal after he made his 55th appearance.