NEW YORK -- Poll the Yankees, and they'll tell you the most significant difference between now and June, between winning and losing, has been their bullpen. And the biggest difference in their bullpen has been the success of Phil Hughes and Alfredo Aceves.

Problem is, having Hughes and Aceves pitch in relief has drained much of the starting pitching depth from their system. And so the Yankees made a move to address that Thursday, acquiring right-handed starter Chad Gaudin from the Padres for a player to be named later.

Gaudin will not immediately assume the fifth starter's role, but his presence suggests that the struggling Sergio Mitre's job is not safe. He should join the Yankees at some point during this weekend's series against the Red Sox at Yankee Stadium.

"I was surprised, but it's not the first time it's happened to me," Gaudin said. "I'm excited to go to New York. I love to win, and that's what they do."

That's what Gaudin, at times, has done as well. Pitching exclusively out of the rotation this season for the first time since 2007, Gaudin, 26, has shown flashes of premier ability but also frequent bouts of wildness. During one late-June stretch, he won National League co-Player of the Week honors by striking out 20 batters, walking three and allowing two earned runs over two victories.

But Gaudin has struggled since then, posting a 5.45 ERA in his seven most recent starts -- five of which have come at PETCO Park, one of the league's most pitcher-friendly stadiums. For the season, he is 4-10 with a 5.13 ERA, though the Yankees were certainly just as interested in the fact that he has fanned 105 batters in 105 1/3 innings.

"He's got a good arm, he can get up to 94 [mph] and he's got a good slider," general manager Brian Cashman said. "He's stretched out and he can give you innings. If you look at his games this year, you've seen that he can dial up and provide quality starts, and, obviously, he also has a chance to struggle at times, too. It seemed like a risk without question worth taking."

Once a top prospect of the Rays, Gaudin has since bounced from Tampa Bay to Toronto, Oakland, Chicago and San Diego. He is 32-35 with a 4.58 ERA for his career, splitting time between the rotation and the bullpen in each of his past two seasons.

For most of Gaudin's two and a half seasons in Oakland, then-Athletics outfielder Nick Swisher was his roommate.

"I just sent him a text message earlier," Swisher said after Thursday's 13-6 win over the Red Sox. "[I'm] happy to have him over here. He's a good dude, he's a competitor and he's going to go out and give it his all every day.

"He's a great guy, a great dude. I think he's going to fit in here real nice."

Initially, Gaudin will slot into the bullpen, where he has a career 4.00 ERA. But if Mitre continues to struggle in the fifth starter's role, the Yankees now have an intriguing replacement. Mitre, who lasted just 4 1/3 innings in Wednesday's win over the Blue Jays, has posted a 7.50 ERA in four starts since taking over for the injured Chien-Ming Wang, pitching fewer than six innings in all of them.

Gaudin, in contrast, has pitched at least six innings in five of his last nine starts.

"He's a guy that's going to come here and give us more depth in terms of choices for starters if we need some," said Cashman, who discussed Gaudin with the Padres prior to the non-waiver Trading Deadline -- before general manager Kevin Towers cut off talks to focus on dealing his ace, Jake Peavy. "I need to get as much inventory as we possibly can. He could be an insurance policy for the rotation if we have an injury -- if we feel we have to make a move there -- or he can help us in the 'pen."

Gaudin will fly to New York City on Saturday and should join the active roster Sunday.