I had a theory back in the draft about the Jaylon Smith pick. I have no proof, so this is pure speculation, but it is based off of various aspects of what went on after the Denver pick as well as the actions and reactions by people in the Dallas Cowboys war room.
My thinking was that they thought they were trading that pick to get back into the first round and they had their backup plan for who they wanted to draft in the second round in case the trade deal (or deals) fell through. I think what then happened was the trade deal(s) fell through and one of the teams above them and after Denver chose the backup plan player (Ogbah maybe?) and the next guy on their board was Jaylon Smith, who they probably planned to take in the third.
If I remember correctly, Stephen was on the phone right up until the last moment of their second round pick likely trying to trade down and when it fell through, they had to take the next guy on their board, which was Jaylon Smith.