Before we all go out and jump off the closest bridge, let's please calm down. Yes, the Mets aren't hitting well. Yes, the Mets aren't winning; but there's still plenty of baseball to be played.
With 64 games remaining in the season, 35 of them are against teams that are sub .500; 24 of those 35 games are against teams that are 10 games under .500; 17 of those 35 games are at home where the Mets are actually playing really well; and seven of those game are to end the season at home.
Furthermore, the Mets are playing 10 more games against the Atlanta Braves this season which gives them lots of opportunities to play catch-up. Atlanta will slow down eventually. How soon I can't say, but they can't continue pitching and clutch hitting the way they are
Since the All-Star break, we've seen that the Braves closer and former Mets closer, Billy Wagner, have been terrible. Wagner blew two consecutive saves after a relatively clean season; he lost only three in his first 25 opportunities.
It's possible that you could say Wagner just had "two bad outings". It's also possible that he's feeling the effects of pitching more than 41 innings this year. When you factor the workload with his age, it's clear he will slow down in the second half.
One of these days, the offense will wake up. While we all hope it is sooner rather than later, later (not too late, though) wouldn't be so bad. Considering what happened in '07 and '08, a team who isn't worn out from hitting too much will be hitting well in late September when it matters most.