Jalen Riddick, 18, was one of five individuals to plead guilty in the case and the first to be sentenced in Chesapeake Circuit Court.
Riddick was among a group of youths charged with jumping Beard after he happened upon a gang-related fist fight in a field near a South Norfolk, Va., Oct. 23, 2011.
Beard, who played for the San Francisco 49ers in the 1960s and was later defensive coordinator for Detroit, had been out for a bike ride at the time. He was knocked unconscious in the attack and said in court he had since been diagnosed with anemia and heart trouble, The (Norfolk) Virginian-Pilot said.
Witnesses testified at Monday's sentencing hearing there was a large presence of people wearing gray bandannas connected to a South Norfolk street gang.
The Virginian-Pilot said Riddick had denied the claims of his co-defendants that he struck the first blow after Beard was surrounded by a group of assailants.