This isn’t Cincinnati. Jay Bruce got a very cold reminder Tuesday night that the Mets traded for him expecting home runs and RBIs as the boos grew louder at Citi Field. The one-time National League leader in RBI, Bruce hit a new low since coming to New York, being pinch hit for with a player who had not had a major-league at-bat since May.“Very difficult, it’s the first time I’ve ever been pinch hit for,” Bruce said (obviously forgetting the eight other times in his career he’d been lifted) after Terry Collins sent him to the bench with a runner in scoring position in the eighth inning of the Mets’ 5-4 loss to the Braves. “I always think I am the best choice. I think everyone in this locker room does. But he’s the manager and I respect his decision and it is what it is.”It turned out to be the right decision. Bruce was on the on-deck circle as T.J. Rivera’s sac fly closed the Mets’ gap to 5-3. With Curtis Granderson on second, the Braves went to the bullpen for left-hander Ian Krol and Collins called the struggling Bruce back. Eric Campbell, who had not had an at-bat in the majors since May 30, slapped a line drive into left field to keep the rally going. “It’s one of the worst things you can do as a manager, pinch hit for a star, one of the elite power hitters in the game,” Collins said. “But my job is try to win the game. In my opinion, I know he’s struggling, I know he has trouble with lefties. I talked to him the inning before. … He looked me right in the eye and said do what you got to do, because he’s a pro.” Bruce was hitting .265 with 25 home runs and 80 RBI in 97 games with the Reds before the trade. The Mets dealt away their second baseman of the future for him with the idea he would be insurance if, as expected, Yoenis Cespedes opts out of his contract next season.Since the trade, Bruce is hitting .176 with four doubles, four home runs and 11 RBI in 142 at-bats. After going hitless in his previous nine at-bats before Tuesday, Collins gave the 29-year-old two days off to clear his head and see if that would get him going.