The Mets did what nobody else had done all season: beat Patrick Corbin. Behind a scalding-hot Jeremy Hefner and a seven-run seventh inning, they handed the Diamondbacks ace his first loss and rolled to a rain-delayed 9-1 rout. Hefner (3-6) allowed just four hits and a run in seven sterling innings, leaving only because the rains came and forced a 1-hour 41-minute delay. But yet another quality start from Hefner shows there might be some quality in the rotation behind Matt Harvey after all, and a season-high seven-run explosion during the interrupted seventh inning turned the Mets’ 11th win in 17 games into a laugher. “We haven’t had that in a while,” manager Terry Collins said. “I know we haven’t scored a lot of runs in this ballpark, so seven is pretty big. It just took an hour and a half to finally get them, that’s all.’’ Collins has come to expect this kind of outing from Hefner. “I expect him to really compete,” Collins said. “He’s going to give us a great effort, keep us in the game. ... We’re kind of expecting that from him right now.’’ Hefner has not allowed more than one earned run in five of his past six starts, pitching to a 1.70 ERA since June 4. He’s turned in quality starts in seven of his last eight, for a 2.20 ERA dating back to May 24. “I’m just making pitches, that’s all that’s changed,’’ said Hefner, who added velocity when he tweaked his delivery to add hip torque. “It’s a little bit of a mechanical adjustment, has added some deception and it’s working right now.