The Pirates sort of seemed like they were treating this game as a house money affair; their best player, Andrew McCutchen was out of the lineup
Bobby Parnell, whom I'd already expressed some concern about, entered the game for the 7th inning and immediately walked Pedro Florimon, and you've heard plenty about this because Parnell was ahead in the count and walked a guy hitting .200. So basically he'd made his own bed right then and there. Then, of course, came the ill-fated Mike Morse comebacker, a ball that seemed ticketed for a double play until Parnell chucked the ball into Center Field. This seemed to be some kind of cosmic mindfuck that involved everything that's gone wrong with the Mets crammed into one play, which happens sometimes. It involved Parnell, who's struggled, actually make a pitch and put himself in a position to get two outs. It involved Daniel Murphy, who for years has been the Shleprock of the Mets, essentially cowering in terror as if he couldn't believe a baseball was being thrown in his direction. And it involved Ruben Tejada, whose career arc could be best described as a tractor stuck in neutral. The play was Tejada's, at least in the sense that he was the one heading for 2nd base, except that when the throw arrived at 2nd base—and the throw did arrive at 2nd base, Parnell couldn't have walked it over there any better—the ball had already sailed into Center Field, because Murphy, as I mentioned, was too busy avoiding the fallout instead of trying to back up the play.
Basically, from this point forward, you could put a fork in the Mets, because they were done. Parnell then Wild Pitched a run home, gave up another 4 hits and 4 runs, got booed off the mound and replaced by Eric O'Flaherty who wasn't any better, and essentially the entire game went down the shitter as what was shaping up to be another close game turned into an 8-1 debacle.
You could, I suppose, say that the Mets were due for a real stinker like this, and the rain delay basically killed the entire team's energy. This isn't a good excuse, but it's the only reason I can think of for everything to break down as completely as it did in the 7th inning. Perhaps after battling the Pirates tooth and nail for 30 innings over the past 48 hours had something to do with it, and the day off they'll have today is probably a good thing because they can sleep this game off like the bad hangover it probably was.