UPDATE: The Angels will receive Brian Stokes in return.
Jerry Crasnick is reporting that the player to be named later will be a "low-salaried" pitcher off the big league roster. Sean Green or Brian Stokes are likely.
Matthews will fill in at center for Carlos Beltran until he is healthy, then likely will be shifted to platoon in right field. I'm curious why the Mets made this type of deal. They already have Angel Pagan as a fourth outfielder, who proved he could play in limited time, but still nearly 350 at-bats.
More details as they become available.