The Indianapolis Colts have received crushing news on their biggest defensive star. NFL Media Insider Ian Rapoport reported Monday that linebacker Robert Mathis is out for the season after suffering a torn Achilles tendon, according to two sources informed of the situation. ProFootballTalk first reported that Mathis suffered the injury while working out on his own in Atlanta. Mathis is in the middle of a four-game suspension for violating the league's policy on performance-enhancing drugs. NFL.com