Pittsburgh (10-16) at New York (14-11)

After Oliver Perez’s breakthrough season four years ago, the pitching-starved Pittsburgh Pirates couldn’t envision their young left-hander wearing anything but black and gold for the foreseeable future.

The New York Mets are glad they changed their minds.

Perez, dealt to New York in the midst of his dismal 2006 season, will face his former club for the second time on Wednesday when the Mets look to extend their winning streak to four games at Shea Stadium.

Perez (2-1, 3.62 ERA) burst onto the scene with the Pirates in 2004, going 12-10 with a 2.98 ERA - tied for the sixth-best in baseball - and a major-league leading 10.97 strikeouts per nine innings.

But that was the last Pittsburgh (10-16) saw of a dominant Perez. His ERA climbed to 5.85 in 2005 and he was a woeful 2-10 with a 6.63 ERA in 2006 when the Pirates gave up on him, dealing him to the Mets (14-11) at the trade deadline for right fielder Xavier Nady.

“He has some upside,” New York general manager Omar Minaya said at the time. “We think Perez has some potential to be turned around.”

That upside was on display last season, when Perez went 15-10 - tied for the Mets’ lead in wins - with a 3.56 ERA and a team-leading 8.85 strikeouts per nine innings.

The left-hander has been up and down in 2008. Perez hasn’t allowed a run in three of his five starts, but he’s yet to work into the seventh inning. He picked up his first loss in his latest outing, allowing five runs in 5 2-3 innings in a 10-5 loss to Washington on Thursday.

“I want to go deeper into games,” Perez told the team’s official Web site, “but sometimes you can’t.”

Perez allowed five runs - all unearned - in six innings against the Pirates last July, striking out nine while taking the loss in an 8-4 Pittsburgh win.

New York’s bullpen certainly wouldn’t mind seeing a dominant effort from Perez. No Mets starter has lasted more than 5 2-3 innings in the team’s last five games.

That’s exactly how long ace Johan Santana went on Tuesday, and he was in line to win before Pittsburgh tied the game in the ninth. The Mets eventually won 5-4 on David Wright’s RBI single in the 11th.

Wright, who began the season hitting .359 with four homers and 19 RBIs, was in a 3-for-29 (.103) slump before taking the ball the opposite way to drive in the winning run.

“In that situation, when you’re struggling, scuffling, you don’t want to try too much,” Wright said.

The Pirates have the worst ERA (6.00) in the major leagues, and aside from the recently released Matt Morris, no pitcher has been more responsible for that than left-hander Tom Gorzelanny (1-3, 8.46).

Gorzelanny’s ERA was under 4.00 in each of his first two big-league seasons, and the 14-game winner was expected to help anchor an improving rotation in 2008. Instead, he’s dragged down an already struggling staff.

He gave up three runs in five innings and walked seven in a 6-2 loss to St. Louis on Thursday.

“I couldn’t find the zone. I don’t know what it is,” said Gorzelanny, who is 0-2 with a 10.45 ERA in three career starts against the Mets. “I’m not happy with what’s going on.”

Nady, who came to the Pirates in the Perez deal, has been one of Pittsburgh’s few offensive bright spots. He doesn’t have a hit in his last two games, but is batting .317 with four homers and a team-high 23 RBIs.

Center fielder Nate McLouth, meanwhile, has homered in three straight games, and is hitting 5-for-13 (.385) with four homers in that stretch.