MIAMI -- The reintroduction of Jason Bay into the Mets' consciousness has taken place slowly. A start against a lefty here. An inning as a defensive replacement there. A pinch-running assignment during a ninth-inning rally.
For Bay to have a meatier role in 2013, he's going to have to show the ability to do more of what he did Sunday: a first-inning grand slam to kick-start the Mets' 5-1, series-sweeping win over the Marlins at Marlins Park.
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"It's his win today," said Chris Young (4-7), who allowed one run in five innings.
Bay, batting seventh, sent a 1-and-0 pitch from Mark Buehrle nearly 400 feet to right-centerfield for his seventh homer of the season. Bay's fifth career grand slam gave the Mets a 5-0 lead and increased his RBI total from 14 to 18.
Sunday's start was Bay's first since Aug. 25. His body of work since then has been that of a fifth outfielder, not a three-time All-Star with a $66-million contract.
On Tuesday, Wednesday and Friday, Bay replaced Lucas Duda in leftfield to help protect Mets leads. On Saturday, he pinch ran for Duda and scored the go-ahead run during the Mets' four-run ninth inning in a 5-3 win over the Marlins.
"I kind of feel like I'm adapting," Bay said. "Small victories. It was one game and it was great. It's not something that I feel was out of character for me. It's just somewhere along the way, we lost it. It's a battle to try and find it."
Manager Terry Collins has long been an admirer of Bay's professionalism in the face of a prodigious drop in production and playing time. He said he did not have a conversation with Bay before deciding to basically use him as Duda's caddie in leftfield and on the bases.
Bay has continued to play hard and show little regard for his body, which is remarkable considering his history of crashing into walls and suffering concussions.
On Sunday, he dived headfirst into foul territory down the leftfield line in an attempt to catch a second-inning foul ball hit by Greg Dobbs. The ball ticked off Bay's glove. His slide finished with his head inches shy of the sidewall.
"I actually thought he hurt his shoulder on that," Collins said. "I said, 'Oh, boy, don't tell me this is another one.' "
But Bay was uninjured other than some contact burns on his arms and hands. He singled to right in his next at-bat and finished 2-for-4 to raise his average to .160.
The Mets (64-70) have won seven of their last eight and are 5-1 on this three-city trip that continues Monday in St. Louis. They put three more games of distance between themselves and the last-place Marlins and moved into a tie for third with the Phillies.
Young picked up his first win since Aug. 2, allowing five hits and a walk with three strikeouts. The Mets' resurgent bullpen pitched four shutout innings.
The game started with Ronny Cedeño hitting a 410-foot blast to centerfield for a double. Justin Turner followed with a drive to right that Giancarlo Stanton overran and watched fall just inside the line for another double.
Cedeño, who apparently was going to tag up on the play, made it only to third, but it didn't matter. David Wright's grounder to short gave the Mets a 1-0 lead.
One swing later, the Mets had a 5-0 lead.
"I thought today was a huge game for him," Collins said. "That's the role he's going to play right now. Come in and get big hits like he did. Hopefully, this is the start of it."