This is the second part of an eight-part series in which Football Outsiders looks at the biggest holes remaining on each NFL team, division by division, going into the offseason. Remember, some of these holes might not actually be holes if teams re-sign their own players, and other holes will be filled during free agency and the draft.
Today, Outsiders looks at the AFC West.
Denver Broncos: Secondary
While Tim Tebow has occupied most of the conversation concerning the Broncos since he became the starter six games into the 2011 season, Denver's biggest problem is in the defensive backfield. Champ Bailey is still one of the league's best cornerbacks, but he will be 34 by the start of the 2012 season. While 2008 was the only season in which he missed significant time, he has played 16 games only once in the past five seasons, and age is likely to take an increasing toll on his availability and level of play. Even if he moves to safety at some point, the Broncos will need to find an answer in his place. The other starting corner, Andre' Goodman, had a surprisingly decent season but will also be 34 by the start of next season. There are no clear replacements for either on the roster. Rookie Chris Harris had a good season as a nickelback but probably isn't ready to start, and the only other corner who saw significant action was Cassius Vaughn, who graded poorly in our game-charting project before going on injured reserve.