A 31-year-old left-handed hitter who was part of Boston's 2007 World Series championship club, Hinske was batting .255 with one home run and 11 RBIs in 54 games with the Pirates.
"There's a lot of benefits to him," Yankees general manager Brian Cashman said. "He knows his role. He's a pro and he's been through the trenches of the American League East and played in the postseason. We're just hoping he can come in here and help us."
The Yankees also received cash considerations along with Hinske, whose 2009 contract is for $1.5 million. He projects as a bench player, helping to back up Alex Rodriguez and Mark Teixeira at the corner infield positions, while also playing the corner outfield spots and serving as a part-time designated hitter and pinch-hitter.
"We look at him as being able to play the corners, if we want to give Al or Tex a day off, or DH one of them," Girardi said. "We feel he can play the corner outfield as well. We think he just gives us some versatility."
Hinske was set to join the team in New York on Tuesday, when a roster move would have been made to activate him for the game against the Mariners, but Hinske's flight from Pittsburgh was delayed due to weather and it was uncertain whether he would arrive in time for the game.
There was no immediate announcement of a corresponding roster move.
During the Yankees' series last week in Atlanta, Cashman had said that he would not seek to add another offensive player despite their recent road struggles, a losing skid that was corrected by winning the series against the Braves and sweeping a three-game set against the Mets.
But the Bombers learned last week that Xavier Nady's chances of returning as an active player had been dealt a serious blow, as the outfielder walked off the field during a rehab appearance at Triple-A Scranton/Wilkes-Barre. That knowledge changed the landscape.
"We thought that we'd have Nady back this week, and unfortunately he had a pretty substantial setback," Girardi said. "Hinske was available, he has the versatility of the infield and the outfield, and he was attractive to us."
While Cashman said he could have called up big-swinging Shelley Duncan from the Minor Leagues instead as a corner outfielder, the Pirates' willingness to pick up part of Hinske's contract helped move the deal along.
"In the role that we're going to use him, there was a [salary] level that we had to get to that made sense for us," Cashman said.
That role is multi-purposed. This season with Pittsburgh, he has played 13 games in right field, six games at first base and three games at third base, and has made 29 pinch-hit appearances, going 8-for-24 (.333) with five walks.
Cashman recalled the Yankees' June 21 loss at Florida as an example of how the Yankees might use Hinske. In the ninth inning of that contest, Girardi could have used another pinch-hit option for a potential game-tying three-run homer, with light-hitting Brett Gardner's spot up.
"We had to use Brett Gardner, because there wasn't that type of choice on the bench," Cashman said.
It worked out in the Yankees' favor, as Gardner ripped a two-run triple, but Johnny Damon walked and Derek Jeter grounded out to end the game. In a similar future spot, Hinske could see duty.
Hinske had signed as a free agent with the Bucs after appearing in his second straight World Series in 2008 with the Rays. Tampa Bay's Opening Day right fielder last season, Hinske delivered 20 homers and 60 RBIs for the American League champions.
Hinske is a former AL Rookie of the Year, earning that honor in 2002 with the Toronto Blue Jays, who had made him their 17th-round selection in the 1998 First-Year Player Draft. He is a lifetime .257 hitter in 957 career Major League games with the Blue Jays (2002-06), Red Sox (2006-07), Rays ('08) and Pirates ('09).
Erickson, 23, was 3-3 with a 2.25 ERA in 21 games, including three starts, with Class A Charleston of the South Atlantic League. He was the Yankees' 10th-round pick in the 2006 First-Year Player Draft.
Fryer, also 23 and a 10th-round pick in 2007, was batting .250 with 15 extra-base hits and 24 RBIs at Class A Tampa of the Florida State League. He was acquired last season from the Brewers in exchange for left-hander Chase Wright.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.