Answer by taking a quote from the following article:

Rex Ryan and his fraternal twin, Rob, were born in Ardmore, Oklahoma, on December 13, 1962, to Doris and Buddy Ryan. When the boys were aged two, their parents amicably divorced. Following the divorce, their mother attended the University of Chicago to earn her doctorate. Rex, Rob, and their older brother Jim moved with her to Toronto, Ontario, Canada, where she secured an administrative position at the University of Toronto.

When his father was hired as the head coach of the Arizona Cardinals in 1994, he offered Rex his first job in the NFL as a defensive assistant, working with the team's linebackers and defensive linemen. After nine straight losing seasons prior to Buddy's arrival, the Cardinals produced an 8-8 record in Buddy's first year as head coach. However, in his second season, the team went 4-12 and subsequently, the entire staff was fired despite the positive performance of the defense.  Ryan went on to coach at three different colleges following his tenure with the Cardinals, though by the time he joined Kansas State in 1999, he was hopeful of a return to the NFL. Ryan received a call from newly named head coach Brian Billick of the Baltimore Ravens, who wanted to interview him for the defensive line coaching position. Having visited a class Ryan was teaching earlier in his career, Billick had been so impressed by Ryan's passion for the game of football that he decided to hire Ryan if he ever attained a head coaching position. When offered the position, Ryan accepted.  In his first year, the defense was ranked second overall in the NFL and second in rushing yards allowed. By his second year, in 2000, the Ravens' defense set NFL records for fewest points allowed and fewest rushing yards allowed. The defense allowed a combined 23 points in four playoff games en route to a Super Bowl XXXV victory, Ryan's only Super Bowl ring, over the New York Giants. The defense consistently performed well in the following years. As a result, Ryan was promoted to defensive coordinator in 2005 following the departure of Mike Nolan, who became the head coach of the San Francisco 49ers. In 2006, Ryan received Assistant Coach of the Year awards from Pro Football Weekly and the Pro Football Writers Association.  Upon the conclusion of the Ravens' 5-11 performance in 2007, the entire staff was dismissed on New Year's Eve. Ryan was one of the candidates interviewed by the Ravens for their head coaching vacancy; however, the Ravens chose to name John Harbaugh as the team's new head coach. Ryan also interviewed with Miami and Atlanta about filling their head coaching vacancies, but the offers went to Tony Sparano and Mike Smith respectively.  Ryan was disappointed by his failure to obtain a head coaching job, but he agreed to return to Baltimore under the direction of Harbaugh, who retained Ryan as defensive coordinator and promoted him to assistant head coach. In 2008, Ryan's final year with the team, the defense was ranked second overall in the NFL. The Ravens lost by a score of 23-14 in the AFC Championship Game against the Pittsburgh Steelers. Ryan's nine-year tenure with the Ravens, during which the defense never ranked lower than sixth overall in the NFL, concluded an hour later when he accepted the head coaching position with the New York Jets.

Did the new team successfully coach?
As a result, Ryan was promoted to defensive coordinator in 2005 following the departure of Mike Nolan, who became the head coach of the San Francisco 49ers.