The Cowboys’ trade acquisition of Joe Milton III was simply a depth move for a backup quarterback to operate behind Dak Prescott — or was it? Former NFL star running back LeSean McCoy isn’t so sure that Prescott’s job will be totally safe. “Listen, if Dak Prescott has a postseason like he’s always had going into that next year … Dak, find a realtor,” McCoy said Thursday on FS1’s “The Facility.” “Because Joe Milton got talent — he can play.” Dallas just signed Prescott to a four-year, $240 million extension before last season, making him relatively untradable with a deal...