T.R. Sullivan has a write-up this morning on the Padilla trade, in which he says the Phillies have a list of players from which they can choose the PTBNL who will complete the deal.
Two of the players Sullivan identifies are Ricardo Rodriguez and Julio Gonzalez, a 17 year old minor league infielder.
So it sounds like the PTBNL being given up by the Rangers isn't a legitimate prospect, or anyone the team is likely to miss.