Mets Offensive Ranks in the National League:
Batting Average: 9th
On-Base %: 11th
Slugging %: 11th
Mets Pitching Ranks in the National League:
Yes, if you look at the other pitching statistics they aren't as good, but that's an easy stat to compare how they have done this 1st half (and it won't be that good in the 2nd half).
Could they use a 5th starter? Of course. Could they use another bullpen arm? Of course. But out of the 17 other teams that are above .500, all but one or two teams couldn't use bullpen help or another starter.
I don't think that we need a major upgrade in the offense (a trade for Kelly Johnson would be nice), but more so that we maximize the team's strengths (large platoon splits) and minimize their weaknesses (Frenchy and Barajas pathetic OBPs). I don't think the Mets need to trade for bullpen help as they have a serviceable arms in the minors (Acosta and hopefully Igarashi). The 5th starter is something they don't have in the minors, and that is where the trade market could improve the team.