There was a time when Matt Harvey might have gotten away with hanging a slider. Even against the most dangerous of hitters, raw stuff buys this kind of leeway. These times, however, are not about the beauty that arises from the blend of an electric arm and an outsized ego. These are times of struggle, of desperation, of a diminished talent waging a battle against his own bruised body. So when Harvey let fly with a slider that floated toward the plate like a helium balloon, there was no suspense. With Giancarlo Stanton standing in the batter’s box, there was only certainty, and then a pop. Stanton cut loose with a powerful swing. Harvey turned his head, the sound alone leaving him resigned to his failure. Smashed with the trajectory of a thinned 2-iron, the baseball barely missed crashing into the metal monstrosity that is used to celebrate home runs here. It was Stanton’s 55th of the season, and the signature moment of Harvey’s latest nightmare on Monday night, when the Marlins hammered the Mets, 13-1. “Nothing’s good,” said Harvey, who was shelled for seven runs in four-plus innings. “It was terrible all the way around. There’s nothing to say.” For the second straight start, Harvey broke from form. Gone were the feeble attempts to slap smiley faces on his awful numbers. Positive slogans were replaced by honesty and rawness and resignation. His words revealed the freshest wounds inflicted by a game that feeds on cruelty.