'Rob Ryan has served as defensive coordinator for four different teams: the Saints (2013-15), Raiders (2004-08), Browns (2009-10) and Cowboys (2011-12). The Raiders had the worst defense in the NFL in 2005, but rebounded to finish No. 3 overall the following year. The Saints had the worse defense in NFL history in 2012, but under Ryan's leadership improved to fourth in 2013. Ultimately, however, Ryan was fired from each job.'