LAS VEGAS — Eight years ago, Brett Veach locked himself into a dark room inside the Chiefs practice facility with the film on replay, asking another member of the front office, Mike Borgonzi, to join him there. Veach had the clicker in his hand. “Look at this throw,” Veach would say, and then he’d move to another play. “And this one.” “Veach,” Borgonzi recalled replying, “It’s May.” Ten months, in other words, before the draft would place Patrick Mahomes in Kansas City. But then again, Borgonzi said, “Some of the stuff he was doing, you didn’t see anyone, even in the NFL, doing.” For everythin…