He was traded to the Padres in December of 2014, and in his one season in San Diego before testing free agency, the 31-going-on-32-year-old, seven-year veteran put up a 2.45 ERA, a 2.57 FIP, 15 walks (2.63 BB/9) and 63 Ks (11.05 K/9) in 53 appearances and 51 ⅓ innings pitched.
Kelley held opposing hitters to a combined .216/.273/.323 line, .224/.267/.400 vs left-handed hitters and .210/.278/.257 vs right-handers.
In his career, Kelley has a .233/.313/.353 vs .233/.292/.419 split vs left and right-handers, respectively.
He features a 91.9 mph fastball, that opponents hit .300 against in 2015 and a slider (82.8 mph average) against which hitters had a .169 AVG.
The Nationals signed Kelley to a 3-year/$15M deal during the Winter Meetings. As he explained it earlier this month, at Nationals WinterFest, things with Washington came together quickly in Tennessee.
"I was actually in Nashville at the Winter Meetings," Kelley said. "I don't live too far away from there, and I was kind of just there to meet some people, talk to some teams if they wanted to get to know me a little better on a personal level and it just kind of came together in the matter of an evening really with the Nationals, and then we had to work through some contract stuff."
News of the deal came out several days before it was officially announced.
"We really wanted to make sure we got through the physical part and we didn't want to do your typical 'say that we've agreed to something' or 'had something in place' because we fully didn't," Kelley told reporters.
"That's why it was kind of like, 'Has he done it or has he not?"
He has. Kelley's contract was announced on December 10th.
"Kelley is another aggressive right-handed pitcher that attacks hitters," Nationals' GM Mike Rizzo said.
"He's got a really good sinking fastball and a wipeout slider and [he's] a guy that's pitched leverage innings for different teams, proved that he could do it in big markets like New York City and was great with the Padres, so we liked what we saw when he pitched against us at times and scouts really liked his demeanor and his aggressive nature on the mound."
Kelley gives the Nats an experienced arm in the back of the bullpen after they struggled to find a late-inning bridge to either of their closers, Drew Storen or Jonathan Papelbon, last season.
"I think the more experience you have in any situation, you're going to get better and allow yourself to thrive," Kelley said.
"So, New York, I closed a little bit for a time and did some eighth inning stuff, I pitched in the seventh inning, I've mopped up innings before in my career. Baseball never fails to throw new situations at you, but I think the more experience you have and the more you've deal with the better you can handle something new thrown your way."
He also has a rubber horse head affectionately known as "Seabiscuit" which he occasionally wears while he stretches before games.
At least that's the rumor.
"Everyone keeps asking me about this horse head... I don't even know what they're talking about."
Also... He's, uh, wearing no.27 again this season, just months after Jordan Zimmermann, who wore it before him, left as a free agent and signed with the Detroit Tigers.
"They asked when I did my physical when I was over at the field the other day, they asked me what number I want and the clubhouse manager had actually already put me down for 27, because I wore that in New York, and I said, 'Is that too soon,' and he said, "Nah, it's just a number, nobody will mind.' So I said, alright, I'll take it."
It's all good though. Kelley said the Nats fans he met at WinterFest in the Walter E. Washington Convention Center have been great and everybody has been welcoming..
"I've asked a few people, 'Are you going to be this welcoming if I give up a homer and cost the game? Some people said, 'Yes.' Some people said, 'No.'"