Irving was the closest Bronco to Texans returner Trindon Holliday on the play, and was blocked into Holliday by Glover Quin. His helmet appeared to impact Holliday's at an awkward angle, and he went down immediately, showing the "fencing response" with his arms involuntarily locked to the sides, while falling to the ground. That reaction is consistent with sustaining a concussion.
Irving remained down and received attention for several minutes near the sideline, but was able to stand and walk to the bench under his own power.
CBS's Jim Nantz announced on the network's broadcast of the game that Irving sustained a concussion, according to the Broncos' medical staff, and is not expected to return.