Matt Thornton. (AP Photo/Alex Brandon)

Upon hearing that he had been claimed by the Nationals and was heading to Washington, Matt Thornton was floored. He didn’t think he was likely to be traded and, once the trade deadline passed, he thought he was in the clear. Then Yankees assistant general manager Billy Eppler told Thornton the news Tuesday. The left-handed reliever was shocked. Then he recovered, packed up belongings and made the drive to Washington from New York.

By the time he arrived in Washington, and joined his new teammates, Thornton’s thoughts had turned to his future with the Nationals and the optimism of a pennant race.

“It’s exciting to come over to a team that’s in first place,” he said, standing in front of his new locker next to his bullpen mates. “When you come into a clubhouse that’s playing so well and is in first place, they obviously have great chemistry and they have a lot of fun. So all my job is now is to fit in and help them have fun and help them win ballgames.”

The acquisition of Thornton helps bolster a Nationals bullpen which has been among the best in baseball but whose production had slipped of late. The Nationals bullpen has allowed 21 runs over the past 33 1/3 innings. Thornton adds experience (he’s almost 38 and has spent 11 years in the majors) and the ability to face batters from both sides of the plate.

The Yankees used Thornton mainly as a left-handed specialist, but he has had success against right-handed batters in his career. This season, right-handers have hit .243 against him with a .704 OPS compared to .250 and .556 against lefties. He relies mainly on his fastball, which ranges from 93 and 97 mph.

“I feel confident [getting right-handers out,” he said. “That’s up to them. I’ve had 1 2/3-inning outings with New York, I’ve had one-third, I’ve had a little mixture of everything. It’s just about workload and what they want from me. I feel good. I’ve learned from mistakes over the years and I’m looking forward to learning some new hitters.”

Because he is a left-handed reliever and limited left-handed batters so well in his career, Thornton has fought to pigeonholed into being considered a lefty specialist.

“I think last year my splits against righties weren’t that good and people kind of ran with that, that I couldn’t get righties out anymore,” he said. “The thing was, in Chicago we had a bullpen that had Nate Jones, myself, Matt Lindstrom, Jesse Crain and Addison Reed. I didn’t need to face righties. … I took that as a little insult and prepared myself to pitch a full inning every day.”

Asked role the Nationals had told him they expected him to fill, Thornton said: “I’m game for whatever they need me for.” Then, the 6-foot-6 reliever added with a smile: “Left-handed, pinch-hit, power-hitter is also a big part of my game.”

To make room for Thornton on the active roster, the Nationals optioned Blake Treinen to Class AAA Syracuse. With Treinen in the fold and capable of providing multiple innings of relief, left-handed reliever Ross Detwiler could be freed up for a more versatile role. But without Treinen, Detwiler remained the left-hander most able to chew through needed innings and, as a result, Thornton would be used as either a situational left-handed reliever like Jerry Blevins or as a full-inning arm.

“Ross has the ability to go multiple [innings],” Manager Matt Williams said. “Matt really has not been that guy. He hasn’t been that guy this year. He’s been a situational lefty, started or finished an inning-type of guy in New York. That may put Det back into that situation where he is our inning-plus guy or the matchup guy. The good thing about having three [left-handers] is that we can matchup the next day and the next day.”

Thornton had a 2.55 ERA in 46 appearances this season with the Yankees but amassed only 24 2/3 innings. He will make roughly $1 million for the remainder of this season, and he is also under contract for $3.5 million in 2015.

The Nationals spoke highly of Thornton’s veteran presence and playoff pedigree. In his career, the only playoff series he appeared in is the 2008 American League Division Series. He pitched 3 1/3 scoreless innings for the White Sox against the Rays. He was acquired by the Red Sox before the all-star break last season but  did not make the postseason roster.

“It’s a motivating factor, period, in my career,” he said. “I feel like I have a lot of baseball left in me. I feel like I have a lot of years ahead of me still. That was a very disappointing time in my career. I got hurt at a very bad time. I think it was about August 10 or so when I strained my oblique, and it set me back pretty bad. I don’t need a whole lot of motivation in the offseason and postseason, but it was very fun facing Boston this year.”

Thornton knew a few of the Nationals from facing them but knew Rafael Soriano as both came up in the Seattle Mariners system a decade ago. Beyond that, he knew little about his new team other than their talent and place in the standings.

“I know they have great arms at the back end,” he said. “It’s just going to be fun to plug in there and see how they use me. I’m looking forward to helping them win.”