It's Captain Janks, a longtime pranker for the Stern show. He set it up by first pretending to be Westbrook's agent. He just looked up the name of an agent in Philly and used that (ESPN didn't check apparently). Then he changed his voice a bit to be BW.
ESPN thought they had a scoop. Instead they got poop.
"Every American has the right to know when their government believes it has the right to kill them"
--Sen. Ron Wyden (D) Oregon