MLB

PEREZ AWFUL IN LAST START

New stadium, same old Oliver Perez.

The Citi Field upgrade clearly hasn’t solved all of the Mets’ problems, including Perez’s inconsistency.

Perez gave a putrid performance in his final spring training start today. The $36 million left-hander failed to get out of the first inning against the Red Sox at Citi Field, walking four batters and giving up a grand slam before getting booed off the mound by most of the 38,695 fans. The Mets lost, 9-3.

Perez threw just 14 strikes in 37 pitches. He continually blew on his hand trying to warm up on a windy day that gave the pitcher problems.

“It was really cold,” Perez said. “I’m not used to pitching in that weather. I just have to understand that sometimes I’m going to pitch on days like that. I have to get ready for Cincinnati because I know it’s going to be cold, too.”

The outing did nothing to provide any confidence that Perez can be counted on as the team’s third starter. The Mets’ starting rotation is viewed by many as the team’s biggest weakness, with the drastic drop-off after ace Johan Santana.

The Mets signed Perez to a three-year, $36 million contract this winter, knowing there would be days like today for the enigmatic Perez. Pitching coach Dan Warthen ripped Perez for being out of shape in late March. The pitcher responded with a strong outing last week against the Orioles, allowing just one run and four hits.

Perez said his struggles today won’t shake his confidence.

“I feel good,” he said. “I understand sometimes you’re going to have games like that. With the fans, I understand they don’t like today’s game. I don’t like it, too.”

Mets manager Jerry Manuel hoped to get Perez a smooth couple of innings today in preparation for his first regular-season start Thursday in Cincinnati.

“This is just a small, small preview of what’s to come,” Manuel said before the game.

The Mets better hope not.

Rocco Baldelli singled to start the game, then Perez started the Red Sox parade. Dustin Pedroia, David Ortiz and Kevin Youkilis drew consecutive walks to push Baldelli across the plate and cause Mets fans to squirm in their big, new comfy Citi Field seats.

After a foul ball out from J.D. Drew, Perez caught a break by snagging a liner back to the mound from Jason Bay. Perez tried to double up Ortiz at second base but threw it into center field, allowing another run to score. The error was charged to second baseman Luis Castillo. Instead of being out of the inning, Perez had to face Mike Lowell, and walked the third baseman to load the bases again.

The early returns on Citi Field are that it’s a pitchers’ park where home runs will be tough to hit, but Jed Lowrie showed what could happen when a hitter connects. Perez left a fastball over the middle that Lowrie drilled over the left-field wall to put the Sox up 6-0.

Perez went 10-7 for the Mets last season with a 4.22 ERA. In his nearly three years in New York, Mets fans at Shea grew accustomed to the up-and-down nature of Perez. It looks like they’ll have to get used to it at Citi Field, too.

brian.costello@nypost.com