ARLINGTON -- Marty Miller's tenure as the Yankees' director of performance enhancement is officially over.

He was relieved of his duties less than 24 hours after rookie pitcher Phil Hughes strained his hamstring, the latest in a series of injuries that has contributed to the Yankees slow start this season.

Pitchers Mike Mussina and Chien-Ming Wang, along with outfielder Hideki Matsui have also suffered hamstring injuries this season. The perception is the hamstring injuries were related to Miller's work with the club.

"At the end of the day we have had so many hamstring issues, and that's something you can't deny," Yankees general manager Brian Cashman said. "[The] 'why' is something I will continue to try to figure through, but it got to the point where perception is a bit of the problem here. Real or not real, perception becomes reality."

Miller was hired by Cashman after spending the last three years as an education consultant with the National Academy of Sports Medicine. He spent nine years as the director of fitness at the Ballen Isles Country Club in Palm Beach, Fla., and worked in the Minor Leagues from 1995-1997. He has a master's degree in performance enhancement and injury prevention.

"Ultimately, I hired Marty, and now, I made the decision to make the change there," Cashman said. "Marty was here to help our players and he did everything he possibly could to do so. Things just haven't worked out, and that's unfortunate."

Cashman received full support from manager Joe Torre.

"I trust Brian Cashman and what he does," Torre said. "The knowledge Marty had certainly was impressive. Does that mean because you know a lot about the body as it relates to baseball? That's what we don't know."

Cashman acknowledged a possible "disconnect" between Miller and the players as part of the issue. He added that there were other factors that could lead to injuries on his team apart from his players' decisions to work or ignore Miller's program. Working with Miller's program was optional and not required.

"To be quite honest, this is where it gets complex," Cashman said. "There's a lot of guys not doing Marty's program. Truthfully, some of the guys who have gotten hurt were doing their own program. That's where it gets [to be] a grey area and complicated in our sport of baseball."

Miller's program included machines and other exercises some of the players were not familiar with. He did provide equipment when it was requested by the players, but there are reports that he was unpopular in the clubhouse.

"There are a number of factors that contribute to [injuries]. But when pitchers come up with hamstring problems? That normally does not happen," center fielder Johnny Damon said. "I think when you get a number of pitchers going down with the same problem, it opens up your eyes and makes you start thinking, 'There might need to be a change.' ... We never wanted to have injuries here. Unfortunately for the team and for Marty, it happened."

Dana Cavalea, Miller's assistant, will take over as the interim director.

"This is as much my failure as anything else," Cashman said. "I take full responsibility. I'm the one who hired Marty. ... There are a lot of variables in play in every aspect of this sport. At the end of the day, this is a result-driven sport and a result-driven industry. Based on the results this far, I felt I had to make a change."

He said it: "It's not a surprise. Alex is one of the most gifted players in the Majors. I'm not shocked all. He's that good." -- Rangers second baseman Michael Young on former teammate Alex Rodriguez being name Player of the Month for April

Pettitte ready:: Coming off a disappointing outing in his last start, Andy Pettitte is looking to rebound with a strong game against the Rangers in the first game of the doubleheader Thursday. Mike Mussina is scheduled to pitch the second game.

"He's done this before," Torre said. "That's where the experience helps. You agonize over it and then you dismiss it."

On April 27 against the Red Sox, Pettitte was charged with five runs on six hits in 4 2/3 innings. Two of his seven appearances this season have been in relief.

"He's a pro," Torre said. "That was the only day where he has not been in the zone, throwing the ball pretty much where he wanted it."