I believe I've figured out what's missing from the NY Mets: a player that is well respected but not necessary liked.
In government hierarchy, unions, or social organizations, he would be called, The Sergeants at Arms:
An officer appointed to keep order within an organization, such as a legislative, judicial, or social body. source Answer.com
With younger teams, the manager can serve in this role, but with a veteran team, it is much more effective if a player assumes the role.
It doesn't necessarily have to be a star or a veteran player, it usually occurs as a natural evolution of a team based on player personalities and the chemistry within a particular clubhouse.
Last week in St. Louis it was discussed, that Albert Pujols would ride a player who didn't go hard into second base until they never did it again. When asked whether Albert was liked or not, the answer was basically that some liked him but all respected him and listened to what he said.
The watershed moment for the 2006 season was when Julio Franco urged Carlos Beltran to make a curtain call. The team would go on to have the best year this core of players has ever achieved, and Franco was clearly the Sgt. at Arms. By 2007, Julio was washed up and the message was old coming from an ineffective player, but since then the position has gone unfilled.
John Harper of Daily News (hat tip to Metsblog) has a a great article today discussing the Mets leadership issues. Harper takes a look at the whole "edge" discussion that was brought up last week, and it appears Gary Sheffield is going to be looked upon as a veteran leader. The most telling part of the article is when Harper talks a lot about what happened after Carlos Beltran failed to slide, costing the team a win; these guys need a player who will call them out.
On this team? I asked a Mets player privately over the weekend if anyone had said a word to Beltran about it, and he shook his head in a "what-are-you-gonna-do?" kind of way. source Daily News