AP

When we wrote this morning about different coaches’ opinions on being forced to allow the Hard Knocks cameras into their training camps, some members of PFT Planet commented that there are so many exemptions to the rule compelling teams to appear on Hard Knocks that some years, there might not be any teams that can be forced to do it.

It’s highly unlikely that there will ever be a season in which every single team is exempt from being required to do Hard Knocks, but theoretically, it is possible for all 32 teams to meet one of the three exemptions. The exemptions are:

1. Teams that have appeared on Hard Knocks in the last 10 years.

2. Teams with new head coaches.

3. Teams that have made the playoffs in either of the last two years.

This year, the only teams that hadn’t done Hard Knocks, didn’t have new head coaches and hadn’t been in the playoffs either of the last two years were the Panthers, Buccaneers, Rams, Titans and Raiders. So if the Bengals hadn’t volunteered, one of those five teams would have been forced to do it. (The five teams that have appeared on Hard Knocks since it re-started in 2007 after a three-year hiatus are the Chiefs, Cowboys, Bengals, Jets and Dolphins.)

Looking ahead to next year, we already know that in addition to the teams that have already been on Hard Knocks, the 2012 playoff teams (Washington, Green Bay, San Francisco, Seattle, Minnesota, Atlanta, New England, Baltimore, Cincinnati, Houston, Indianapolis and Denver) are exempt. So half the league knows right now it can’t be forced to do Hard Knocks next year.

Add to that list all the teams that make the playoffs this year. A lot of this year’s playoff teams will be the same as last year, or will be among the five teams that have already been on Hard Knocks, but we could easily see the Saints win the NFC South, the Eagles win the NFC East, the Bears win the NFC North and the Lions, Cardinals or Titans get a wild card berth to add themselves to the Hard Knocks exemption list by making the playoffs.

That would leave only 10 teams: The Bills, Browns, Steelers, Jaguars, Chargers, Raiders, Giants, Panthers, Buccaneers and Rams. And at least a few of those teams are likely to have new coaches next season.

So there won’t be many options for the NFL if it decides to force some team to appear on Hard Knocks. The league office and HBO will still be hoping that a team with compelling storylines volunteers.