Gary Kubiak is “really excited” about Trevor Siemian

With all the chatter regarding Denver quarterbacks focusing on the guys who left (Peyton Manning and Brock Osweiler), the broken-glass emergency addition (Mark Sanchez), the flirtation gone nowhere (Colin Kaepernick), and the first-round rookie (Paxton Lynch), no one is talking about the guy who, in theory, could end up winning the job. He’s Trevor Siemian, a…