The New York Post's Joel Sherman and George King say that the two players coming back are Triple-A reliever Mark Melancon and infielder Jimmy Paredes, with the Astros paying $4m of Berkman's remaining salary.
Sherman:
The Yankees do not consider either among their top 10 prospects, and have felt Paredes' defense is weak enough that he ultimately will have to move to the outfield.
More on the players after the deal is confirmed. We're not wasting time doing research like we did with Anthony Gose, who was an Astro for about as long as it took to go to Baseball-Reference.