NEW YORK -- Hoping to tweak their roster for a final push for the postseason, the Yankees made significant alterations on Friday, demoting outfielder Melky Cabrera and cutting ties with veteran Richie Sexson.

The move installs rookie Brett Gardner, promoted from Triple-A, as the Yankees' primary starting center fielder during a crucial stretch in which they will play 28 of their final 41 games against clubs with winning records. New York also added utilityman Cody Ransom to provide versatility off the bench in Sexson's place.

Cabrera took the move with some surprise, embracing teammates in the clubhouse before packing his belongings. The 23-year-old was New York's Opening Day center fielder, but manager Joe Girardi did not start Cabrera four times over the team's recently completed 10-game road trip to Texas, Anaheim and Minnesota.

"That's their decision, and I'm going to do whatever they say, go down there and work hard and try to come back," Cabrera said through an interpreter. "I started good, but my average went down, and I've just got to go to Triple-A."

Cabrera was batting .242 with eight home runs and 36 RBIs in 117 games. He has regressed offensively from last season, a point that Girardi and general manager Brian Cashman established before making the move.

"We just felt it was time for him to go work on some things," Girardi said. "You can't forget how young Melky is, and sometimes it's difficult to work on things here. We talked about some things offensively, we talked about some things baserunning. We felt that Melky has grown defensively as a player, but we just felt it was time now."

Cabrera had just three hits in his past 26 at-bats for New York, though he said he "never" expected to be sent to the Minors at this point in the season.

"He's a better player than this, and he knows it," Cashman said. "He's struggled, and sometimes the best way to get yourself going is to take a step back. He was working hard up here. The performance just didn't follow. In his case, there was somebody pushing from within."

Gardner, who turns 25 later this month, had appeared in 17 games for the Yankees earlier this season, batting .153 with no home runs, seven RBIs and five stolen bases in 59 at-bats. He was batting .296 with three home runs, 32 RBIs and 37 stolen bases at Triple-A. Gardner said that his prior experience might help him in his second tour of duty.

"I'm obviously very excited," Gardner said. "I've been feeling really good down there and swinging the bat well. Hopefully I can continue some of that success I had down there at this level."

Sexson represented a low-risk acquisition for the Yankees, who signed the veteran to a contract on July 18 after he was cut loose by the Mariners. Primarily assigned to play first base against left-handed pitching, spelling Jason Giambi, Sexson didn't adjust with flying colors to a reserve role, hitting .250 with one home run and six RBIs in 22 games.

"We were going to get more versatile for our club, and we felt it was difficult what we were asking, in a sense, Richie to do," Girardi said. "Richie had never really done that."

Cashman said that he still believed Sexson could be an everyday player elsewhere in the league. If he signs elsewhere, another club would be responsible to pay only the pro-rated Major League minimum, as the Yankees had.

"Sporadic play, I don't think, is conducive to where he's at in this stage of his career," Cashman said.

Girardi said that Gardner will be offered playing time while he is up with the big league club, probably with outfield alignments similar to the one the Yankees used on Friday against Kansas City. Gardner started in center field while Johnny Damon served as the designated hitter, with Xavier Nady and Bobby Abreu manning corner outfield spots.

While on the road trip, Girardi had said that he also believed Damon was healthy enough to play center field on a regular basis as the Yankees try to make up their deficit -- 9 1/2 games behind the first-place Rays entering play Friday -- in the American League East.

It is likely that Cabrera will be recalled when rosters expand to 40 players on Sept. 1, though the Yankees would not rule out bringing him back sooner if necessary. The Yankees held on to Cabrera despite a number of trade proposals over the offseason, most notably in discussions with the Twins for Johan Santana. Cashman said that he did not regret that stance.

"Melky Cabrera, I believe personally, is without a doubt an everyday center fielder in the big leagues," Cashman said. "But he has struggled here for an extended period of time, which placed him in jeopardy to be sent down, because someone else behind the scenes named Brett Gardner has pushed himself into the conversation."

New York also made an additional roster move before Friday's game, placing right-hander Dan Giese on the 15-day disabled list with right shoulder tendinitis and recalling right-hander Chris Britton from Triple-A. Darrell Rasner will start on Tuesday in Giese's place, Girardi said.

Cashman said that the multiple moves were not made as a knee-jerk reaction to the Yankees' trip, on which they were swept in Anaheim and played one of their sloppiest games of the season on Wednesday at the Metrodome. He noted that the Yankees' inconsistencies went beyond Cabrera, the No. 9 hitter, and Sexson, who was brought in as a spare part.

"You can take Melky's name and change it with a lot of guys on this field right now that are making a hell of a lot more money," Cashman said. "They're better than what they've shown, too."