In recent years, HBO has had a tougher time getting teams to come on the show, with nobody agreeing to take on the extra cameras in 2011. Last season, it was the Miami Dolphins who let HBO into their headquarters, catching the memorable release of Chad Johnson.
Hard Knocks was originally aired in 2001 with the Baltimore Ravens, who were defending their Super Bowl championship at the time. The Dallas Cowboys were then featured the next year before the show took a five year hiatus.
The Bengals were the team shown in 2009, bringing in the highest ratings of any team to that point. It was unclear whether HBO was going to be able to get a team on air this season, but the problem now seems to be averted.