Owning a fastball that reaches the mid 90s, a slider and a changeup, the 24-year-old Dunn attended Spring Training with the Yankees and left a positive impression.
He started the season with Double-A Trenton and was promoted to Triple-A Scranton/Wilkes-Barre on July 17, combining to go 4-3 with two saves and a 3.31 ERA in 38 relief appearances and allowing just two of his 12 inherited runners to score.
A 33rd-round selection of the Yankees in 2004 from the Community College of Southern Nevada, Dunn hit .160 (30-for-187) in 66 games in 2005 and 2006 before being moved from the outfield to the mound, where he had pitched in high school.
"Being a converted guy was easier for me, because some guys, you've got to teach them [pitching] from the windup or the stretch," Dunn said. "I knew what type of pitches I was going to be throwing, so it was just fine-tuning it from there.
"[Hitting was] what I did my whole life. Of course I wanted to keep going on, but I just wanted to keep having a jersey on my back. Through pitching was how I was going to keep it."
With his backup plan, Dunn has beaten the odds to make it to the big leagues and Yankees manager Joe Girardi said he would allow him to get acclimated slowly.
"We'll try to get his feet wet and go from there," Girardi said. "He's a young man who's never been here, and you don't want to necessarily bring him into a tough spot. We'll see where we're at."
Girardi stressed that he still considers Phil Coke and Damaso Marte to be the Yankees' primary left-handed relievers, but they do have additional help.
New York also recalled familiar faces in right-handers Mark Melancon and Edwar Ramirez from Triple-A on Tuesday, as well as catcher Francisco Cervelli and utility infielder Ramiro Pena.
Girardi said that bullpen arms were a priority with Joba Chamberlain seeing shorter outings under the new "Joba Rules" as well as the bruised right forearm that will force Sergio Mitre to miss a scheduled start Thursday, with Chad Gaudin filling in against the Blue Jays.
"We felt that we needed some pitchers," Girardi said. "There's some clubs that have some left-handers that we're facing, and we think there's value in bringing guys up to see what the feel is like here."
Cervelli is making his second stint with the Yankees after spending two months with the club beginning in early May, filling in behind catchers Jorge Posada and Jose Molina.
Girardi said that it would be a luxury to have a capable third catcher like Cervelli, who hit .269 (21-for-78) in 25 games this season and has bounced back after suffering a bruised left hand last month.
"I learned so many things," Cervelli said. "I'm so happy to be here again. I had to learn how to control my emotions and enjoy my time working with the pitchers. I've been working every day on that, because I've got so much energy."
Melancon is up for the third time in 2009, looking to improve where he left things upon his last departure in early August. Each of his last four appearances were scoreless, and in nine games with New York, Melancon is 0-1 with a 3.18 ERA.
"I want to contribute to this team that's doing great," Melancon said. "My goal is to be on the playoff roster, definitely. There's a full month and that's a lot of time. I'll throw strikes and do what I've done, and consistency pays off."
Pena is also appearing for the third time this season in a Yankees uniform, having last been on the roster Aug. 21 before being optioned to clear room for Marte. Pena hit .277 (26-for-94) in 53 games for New York, appearing at third base, shortstop and second base.
"He's going to play," Girardi said of Pena. "I might use him late in games to spell Jeter a day or spell Robbie [Cano] a day. We'll use him as we see fit."
Ramirez broke camp on New York's Opening Day roster but made just 15 appearances before being sent to Triple-A, owning a 5.19 ERA and having walked 15 batters in 17 1/3 innings.
Upon his demotion, Ramirez acknowledged there had been a problem and promised to correct it in the Minors and did, walking just 16 batters in his next 51 frames.
"I worked over there a lot, and right now it's better," Ramirez said. "Everybody has to throw strikes, and if you throw strikes, you can pitch anywhere. I feel a little stronger. I'm here to pitch in whatever situation. I'm here to do my job like I did last year."
Girardi said that the Yankees likely would summon more players from the Minor Leagues this month, though they are mindful not to promote players if there will not be opportunities to contribute.