Shaun Marcum is new to the Mets, but in some sense he felt at home yesterday as he arrived at the team’s spring training complex. Making the rounds throughout camp was Mets special assistant J.P. Ricciardi, who as Blue Jays general manager drafted Marcum in 2003 and watched him develop over the next six years. Across the clubhouse from Marcum’s locker was John Buck, who served as the right-hander’s catcher with Toronto in 2010. Ricciardi pushed for the Mets to sign the 31-year-old Marcum after R.A. Dickey went to the Blue Jays in a seven-player December trade. Marcum received a one-year contract from the Mets last month worth $4 million, but the value of that deal could reach $8 million with incentives. “I’ve always been a big fan of his,” Ricciardi told The Post yesterday. “We drafted him in the third round in Toronto — he was a shortstop/closer in college. We ended up making him a starter and he got to the big leagues. You don’t forget the guys that compete and do well for you, and he’s been one of them.” Marcum went 7-4 with a 3.70 ERA in 21 starts for the Brewers last season, missing a month with elbow soreness. If he can remain healthy, the Mets expect Marcum to provide 200 innings and battle hitters, with his changeup leading the way. For his career, Marcum is 57-36 with a 3.76 ERA. Maybe his best season came with the Blue Jays in 2010, when he went 13-8 with a 3.64 ERA, with Buck as the team’s primary catcher. “You look back at [Marcum’s] numbers and he’s pitched in two hitters’ parks, Milwaukee and Toronto, plus he pitched in the American League East for a long time,” Ricciardi said. “So he’s got a track record behind him on top of me being able to vouch for him, so those all go hand and hand.” “He’s also a great fielder — the guy should have won a Gold Glove. He’s going to be able to help himself with the bat. If Shaun is healthy through the year, I expect good things from him.”