The Bills public relations department formally announced the move Wednesday evening:
The legendary safety spent plenty of time with Ryan when the current Bills head coach served as the Ravens defensive coordinator from 2005 to 2008. Ryan was also the Ravens defensive line coach during Reed's first three NFL seasons.
The two crossed paths again in 2013 when Reed appeared in seven games for Ryan's New York Jets.
During his esteemed playing career, Reed was renowned as one of the league's premier ball hawks. Over the course of 12 seasons, Reed tallied 64 interceptions, which ranks seventh all-time. The University of Miami product returned seven of those picks for touchdowns—good for the 11th-best mark in NFL history.
CBS Sports' Jason La Canfora was quick to praise the Bills' acquisition of the nine-time Pro Bowler and 2004 Defensive Player of the Year:
Reed will arrive in Buffalo with a chance to help mold a Bills secondary that suffered through an inconsistent 2015 season.
During Ryan's first year in Buffalo, the Bills ranked 19th in opponents' average passing yards (248.3) and tied for 22nd in touchdown passes allowed (30). Buffalo also ranked fourth worst behind the New Orleans Saints, Indianapolis Colts and New York Giants with 59 passing plays of 20-plus yards allowed.
However, the Bills did excel by other measures. They allowed a ninth-ranked 6.8 yards per pass attempt and limited opposing passers to a quarterback rating of 83.3. And with a core comprised of Stephon Gilmore, Ronald Darby and Corey Graham leading the way, there's plenty of talent for Reed to work with.
There could also be some emphasis on interception-return playmaking in practice, as CBS Sports' Will Brinson joked:
Since Ryan is already lauded as a defensive guru, it should be fascinating to see how things play out with Reed assisting with the defensive backs' development.
Tactical missteps throughout the 2015 season cost the Bills a shot at capturing their first postseason berth since 1999, but they flashed enough promise to justify sleeper status in 2016.