Posey replaces Chris Clemons, who was cut Tuesday -- one day after learning he'd miss four to six weeks with a sprained knee.
Posey gives the Redskins something Clemons could not: a veteran backup at linebacker, both inside and outside. Posey will also rush as an end; he has 20.5 career sacks.
He likes playing in Williams' defense because of the attacking nature.
''You get to blitz,'' he said. ''You can come from anywhere. It was a lot of fun.''
Redskins secondary/corners coach Jerry Gray also coached
''He reminds me a lot of Marcus Washington,'' Gray said. ''He may not make as many plays. But we'll give him the chance to rush the passer. He'll bring a lot of pressure for us.''
Redskins safety Pierson Prioleau
played three seasons with Posey in
''He's very solid,'' Prioleau said. ''He's smart and he goes where he's supposed to be. He's a big strong guy who can rush the passer and he'll shut the door in the running game.''