All but clinched? They're third in their own freaking division after having lost to KC (equal records, lose the tiebreaker on divisional record), and Cincinnati, New York, and Jacksonville are all only one game back. Right now, Denver sits in a very precarious 6th seeding in the AFC, which would mean an a**-whipping in San Diego if the playoffs started today.
I was being partially sarcastic. Denver's got a tough schedule, and losing to their divisional opponents really hurt.
Of course, the teams you cited have tough schedules too, New York excepted. Jacksonville can and will choke. Cincinatti's schedule is pretty difficult. Don't leave the Dolphins out of the hunt, especially if the Jets lose a game both to Miami and to someone else.