Because of an injury that may deny the Mets the services of Duaner Sanchez for the remainder of the season, general manager Omar Minaya was forced to abandon his ambitious plans to upgrade the Mets' rotation and seek a trade to reinforce the damaged bullpen.

Before the Mets learned of the injury Sanchez suffered as a passenger in a taxi in Miami late Sunday, they were involved in discussions that would have brought Astros pitcher Roy Oswalt to Shea Stadium in a three-way trade with the Astros and Orioles that would have sent Lastings Milledge to Baltimore, Miguel Tejada to Houston and Adam Everett to the O's. Those talks occasionally overlapped with the Mets' effort to acquire Jason Schmidt, another power starter, from the Giants

Those three-way talks "lost steam" late Sunday, according to Minaya. And by the time they might have been renewed Monday morning, the general manager had changed his focus.

By Monday afternoon, Minaya had completed a deal with the Pirates that brought Roberto Hernandez back to the Mets to serve in the role he filled for them last season -- setup relief, the role that Sanchez has filled so well until he suffered a dislocated right shoulder Sunday night after they had flown from Atlanta to South Florida.

Sanchez has been assigned to the 15-day disabled list with a Grade 4 separation. He is to be reexamined within a week, according to Minaya. If it is determined that surgery is required, he will miss the remainder of the season. If surgery isn't needed, he will miss four to six weeks.

And so, the remarkably smooth ride that has brought the Mets to the threshold of their first division championship since 1988 has hit a significant speed bump that could undermine the team's postseason aspirations. Sanchez has been an integral component in the bullpen that has the lowest ERA in the big leagues.

In an effort to soften the blow of losing him, Minaya traded right fielder Xavier Nady for Hernandez and faded left-handed starter Oliver Perez. The departure of Nady has prompted the club to recall Milledge, the rookie outfielder and the Mets' top position-player prospect who made an uneven 24-game big-league debut earlier this season when Nady, and then Cliff Floyd, were unable to play.

A right-handed hitter, Milledge is expected to share right field with left-handed-hitting Endy Chavez and thereby enhance the Mets' running game. The loss of Nady, though, clearly diminishes the Mets' power. Milledge's immediate availability to the Mets may be an issue because was ejected from Norfolk's game Sunday night and may face discipline. The International League is investigating the incident in which the 21-year-old outfielder was ejected in the first inning by home plate umpire Mike Estabrook.

Milledge had taken exception to a called third strike. He argued with the umpire, threw down his bat and approached Estabrook. One report said Milledge bumped the umpire and that Estabrook backtracked to regain his balance as Norfolk manager Ken Oberkfell ran to intercede.

The Mets' Minor League department at Shea Stadium said it was unaware of a bumping incident, but the International League office is reviewing the situation and awaiting delivery of a videotape of it. The Mets wouldn't be obligated to recognize any discipline imposed by the International League.

Milledge was batting .277 with seven home runs, a .453 slugging percentage and 35 RBIs in 278 Triple-A at-bats. He batted .233 with a .419 slugging percentage, three home runs and 12 RBIs in 86 at-bats while with the Mets from May 30-June 30.

Hernandez, 41, was among the most valuable assets the Mets had last season, when he produced a 2.58 ERA, four saves and an 8-6 record in 67 appearances. But even his fine work last season wasn't quite as effective as what Sanchez provided in the Mets' first 104 games -- a 5-1 record and 2.60 ERA in 49 appearances covering 55 1/3 innings.

And Hernandez this year hasn't been nearly as effective as he was last season. He had an 0-3 record, two saves and a 2.93 ERA in 46 appearances -- 43 innings -- with the last-place Pirates. The Mets weren't particularly impressed with Hernandez's stuff when they faced him July 4 at Shea. He was the losing pitcher and Sanchez the winner in a 7-6 Mets victory.

Perez, already assigned to Norfolk, was one of the bright young stars in the National League two years ago, but has faded quickly since then. He had a 2-10 record and 6.63 ERA in 15 starts this season before he was assigned to the Minor Leagues on June 29. In six starts with the Pirates' Triple-A Indianapolis affiliate, he has a 1-3 record and 5.63 ERA in 32 innings.

Before his demotion, his innings, walks and strikeouts had gone from 196, 81 and 239, respectively, in 2004 to 103, 70 and 97 in 2005 to 76 and 51 and 61 in 2006.

Nady was understandably disappointed by the trade, one he recognized as the proverbial penthouse-to-outhouse move. With the change of address, he lost 24 games in the standings.

"You work all year to get where you are and then something like this happens. It's tough," Nady said. "I was out on the beach with my fiancée when I saw I missed about seven calls on my cell. Then I talked to Omar. He thanked me and I thanked him for the opportunity."

Minaya indicated the injury to Sanchez "moved us more in the direction" of dealing Nady.

Nady batted .264 with 40 RBIs and 14 home runs in 265 at-bats, having missed considerable time -- May 30-June 18 -- because of an appendectomy. He has been playing with a cracked bone in his right wrist.