This article on ESPN: http://m.espn.go.com/nfl/story?storyId=12211433 is reading interesting.
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The league found earlier this week that 11 of the New England Patriots' 12 game balls were significantly underinflated during the AFC Championship Game, ESPN's Chris Mortensen has reported. In that game, the Patriots' equipment staff supplied balls to referee Walt Anderson at the required two hours, 15 minutes before the game for inspection. As per NFL policy, Anderson marked each ball with his approval and ultimately returned them to the Patriots' ball boys.
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Notice it doesn't state that Anderson tested/weighed the balls prior to the game?