MILWAUKEE — If anyone can work his way out of a slump it’s J.D. Martinez, which is why the Mets aren’t overly worried about the slugger’s current 0-for-35 streak. But with the Mets running out of games and struggling to produce runs, the veteran DH needs to snap out of this fast. “He’s close, he’s not far off,” hitting coach Jeremy Barnes told the Daily News this weekend. “But the little things matter.” The “little things” in the case of Martinez are mechanical. Jose Iglesias once described the baseball language of the 37-year-old by using the word mechanical, which is no surprise to anyone who has followed his career. Martinez loves hitting, he loves talking about the techniques and philosophies of hitting and is often the teammate others turn to when they need hitting advice. Mark Vientos has called him “coach J.D.,” Jesse Winker recently showed him videos of his gather to get his input and Iglesias credits some of his success at the plate this season to the weighted ball exit velocity program that Martinez turned him on to during their brief time together in Triple-A Syracuse this spring. But right now, it’s his own mechanics he’s struggling with. “He’s getting out of positions,” Barnes said. “He’s getting into different positions and he’s having to work out of those positions, and the barrel is not where it normally is. It’s just taking a little millisecond longer to get there. So he’s just having a hard time.” This would explain Martinez’s decreased barrel rate this season. According to Statcast, Martinez isn’t barreling the ball as often as he typically has throughout his career. He isn’t squaring up as many balls, his exit velocity has decreased and lately, he’s been hitting the ball on the ground more than he usually does. Especially considering his entire hitting foundation is predicated on being able to get the ball in the air. When he’s out of position and late — even if it’s only a millisecond late — it changes his swing path. “He’s getting a little forward, in my opinion, and then, he’s having to work out of that and loses the barrels,” Barnes said. The Mets gave Martinez a day off in Atlanta earlier this week. Martinez has been working in the batting cages and watching a ton of video to get back to hitting and hitting for the power he’s known for. They intended to use him in the two postponed games against the Braves, but without being able to play those, they had him in the lineup Friday in Milwaukee, hoping the results of the work he’s been putting in would show on the field. Martinez went 0-for-3, though he did reach base on an error. The Mets gave him the day off again Saturday. They don’t see him pressing too hard and they don’t see him overthinking it. They see an eager hitter who has worked through slumps in the past sticking to his process. “That’s the thing about JD, he’s a pro,” Barnes said. “He wants to help the team, he wants to do all those things, but he’s not taking it out on people and he’s not overly stressed. He understands the process, and he’s just in it right now. He’s just trying to get out of it.” Martinez’s last home run was Aug. 30 against the Chicago White Sox. To be fair, the Mets need to see more offensive production from Brandon Nimmo, Pete Alonso and Winker if they want to be able to continue playing into October. Run production has to come from somewhere and someone other than Mark Vientos has to step up. The stars need to play like stars. The Mets think Martinez will show his star-power again this weekend. “It’s a matter of putting in the work, so at some point he’s going to break out,” Barnes said. “I think he’s going to have big at-bats for us.”