If Papelbon's slider can be a go-to pitch along with his lethal fastball and nasty splitter, opposing hitters might be in serious trouble.
"I threw it well today," Papelbon said of the slider. "I threw that pitch a lot today. I threw it in to some left-handers and Doug [Mirabelli] said that it was a good solid pitch for me. It's just a matter of getting it to the point where I can throw it any pitch, any count, any situation. I think it will be there by the time Spring Training [ends] and I'll go into the season being a three-pitch closer."
Though Papelbon didn't necessarily need to develop another pitch, the Red Sox certainly have no complaints with him doing so.
"It's a third option," said Boston manager Terry Francona. "That's why we have Spring Training, aside from building up arm strength and getting ready for a season. Again, for certain hitters, it might be a pretty good weapon. Put something in the back of somebody's head. But when he goes with that fastball and he commands and that split, that's what makes him Pap. But we do like the fact that he's working on it -- because if he's going to throw it, he needs to have confidence in it. There are times when he will throw it. But those other two pitches are pretty special."
In Tuesday's outing against the Mets, Papelbon retired all six batters he faced, striking out two of them. Over five Grapefruit League outings, Papelbon has a 3.00 ERA.
"I think that those first couple of outings for me were tough just because you're getting the dust off," Papelbon said. "I think finally now my body is starting to get accustomed to using those muscles that I haven't used in so long this offseason. Just my overall body awareness and fluidness is a lot better and that's allowed me to get to the plate and deliver the pitch better, and I feel like I have that extra little oomph on my fastball now that I didn't necessarily really have in my first couple of outings."
After making the American League All-Star team in his first two seasons and putting up gaudy numbers in the process, why did Papelbon add the third pitch?
"One, I used to throw it when I was starting, so it's not like it's a new pitch really," said Papelbon. "Two, it's a natural arm slot for me to throw this pitch. It's not like I'm going out of my delivery to execute this pitch. To me, it's just a matter of staying one step ahead of the competition."
Papelbon isn't naïve enough to think he can just stay the same and maintain the numbers he's put up.
"You can't just say, 'It's been working, it's been working, it's going to work another year,'" Papelbon said. "Hitters start seeing you more. It's almost like you just have to keep making your adjustments and staying ahead of the game. The same things aren't going to work for me now that I'm 26, 27 than when I'm 36, 37. It's the same type of concept. [I'm] just trying to stay one step ahead, really."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.