Via USA Today's Bob Nightengale, we know (and quickly, I might add) the identity of the player to be named later in the Darwin Barney trade:
Martinez was signed as an international free agent out of Venezuela by the Dodgers in 2011. He turned 20 about a month ago and has been having a decent year for Great Lakes in the Midwest League: 3.44 ERA, 1.213 WHIP in 19 starts covering 109⅓ innings. He's walked just 19 in those innings, and good control has appeared to be his strong suit in his minor-league career so far (70 walks in 306 innings).
This seems like a good return to me. You can see Martinez' complete minor-legaue record at this baseball-reference.com link. Nothing's been officially announced, but given his track record in the Midwest League, he could be assigned to the Kane County Cougars.