I did find this from the Washington Post;
The NFL issued a written statement that said: “The Management Council Executive Committee determined that the contract practices of a small number of clubs during the 2010 league year created an unacceptable risk to future competitive balance, particularly in light of the relatively modest salary cap growth projected for the new agreement’s early years. To remedy these effects and preserve competitive balance throughout the league, the parties to the [collective bargaining agreement] agreed to adjustments to team salary for the 2012 and 2013 seasons. These agreed-upon adjustments were structured in a manner that will not affect the salary cap or player spending on a league-wide basis.”
Redskins to lose $36 million in cap space over two years [updated] - The Insider - The Washington Post