Billy Davis ( American football ) Billy Davis ( born November 5 , 1965 in Youngstown , Ohio ) is an American football coach in the NFL for the Cleveland Browns . He is the linebackers coach . He previously served as the defensive coordinator for the Arizona Cardinals . He was the defensive coordinator for the San Francisco 49ers from 2005 through 2006 . Early life . Billy Davis was born on November 5 , 1965 in Youngstown , Ohio . His father , Bill Davis , coached in the NFL for 13 years , included the six years he was the Cleveland Browns ’ vice president of player personnel . As a kid , Davis was hired to be a ball boy for Dick Vermeil in Philadelphia and Don Shula in Miami . College years . Davis attended the University of Cincinnati and was a quarterback and wide receiver on the football team from 1985 to 1988 . Coaching career . Michigan State . Davis began his football coaching career as a graduate assistant for the Michigan State Spartans . Pittsburgh Steelers . In 1992 , Davis entered the NFL as the defensive assistant for the Pittsburgh Steelers . For most of his football career , Davis had played and coached on the offensive side of the ball , but under head coach Bill Cowher , Davis coached the Pittsburgh defense for three years . Carolina Panthers . In 1995 , under coach Dom Capers , Davis spent four years with the newly created Carolina Panthers . In his second year with Carolina , linebacker Kevin Greene finished first in the NFL in sacks with 14 . 5 , and Lamar Lathon finished second in the NFL in with sacks with 13 . 5 . Both linebackers went to the Pro Bowl that year . Cleveland Browns . In 1999 , Davis spent a year as a defensive assistant and linebackers coach with the Cleveland Browns . Green Bay Packers . In 2000 , Davis went the Green Bay Packers were he spent the year as a defensive assistant and line coach . Atlanta Falcons . Davis the went to the Atlanta Falcons in 2001 , were he spent the next three seasons as the linebackers coach under Dan Reeves . Davis helped then defensive coordinator Wade Phillips implement his new 3 - 4 defense . During Davis ' three years at Atlanta , linebacker Keith Brooking went to the Pro Bowl each year . New York Giants . Davis was the New York Giants linebackers coach in 2004 . According to defensive coordinator Tim Lewis , Billy commanded the room whenever speaking to players and compiled blitz packages , a job usually done by the defensive coordinator . San Francisco 49ers . On February 6 , 2005 , Billy Davis was hired by San Francisco 49ers head coach Mike Nolan to be the defensive coordinator on the team after a six hour interview . One of the reasons Davis got the job was because he had experience with the 3 - 4 defense that Coach Nolan wanted to implement in San Francisco ' s defense and a recommendation Nolan got from New York Giants defensive coordinator Tim Lewis . 2005 Season . However , Davis seemed to have difficulty improving the defense . In his first season as the 49ers defensive coordinator , the team ranked last in the NFL in total defense in 2005 , averaging 25 . 8 points a game , a 44 . 4 % third - down efficiency , and allowing 428 points that season . 2006 Season . In 2006 , Davis ' defense was ranked 26th in the NFL . Monte Poole of the Oakland Tribune criticized Davis in October , saying " the defensive coordinator Billy Davis , who drifts between the 4 - 3 scheme and the 3 - 4 scheme , not only has been incapable of masking these deficiencies but also seems to find ways to accentuate them . " As soon as early November , rumors began to swirl that Davis could be fired at the end of the season , if not earlier . Although the second half of the season saw strong performances from cornerback Walt Harris and linebacker Brandon Moore , by the end of the season , the 49ers defense had allowed 412 points in 16 games . On January 3 , 2007 , Nolan announced the Davis had been fired stating that " After an evaluation period , we felt this was the right time to make this move " . He was replaced by San Diego Chargers linebackers coach Greg Manusky . Arizona Cardinals . On January 19 , 2007 , just 15 days after he was fired from the 49ers , Davis was hired as the linebackers coach for the Arizona Cardinals . On February 18 , 2009 , Davis was named the team ' s defensive coordinator after former defensive coordinator Clancy Pendergast was fired . Davis was let go after the 2010 season after the Cardinals ' poor performance on defense which ranked 31st against the pass , 32nd against the run and 31st overall . Cleveland Browns . On January 31 , 2011 it was announced that Davis was hired as the linebackers coach . Personal . Billy Davis lives with his wife , Sherry , and five children : Monica , Brooke , twins Grace and Ava and son Billy .