What's transpired at One Bills Drive since the end of the 2014 regular season:
March 9 -- Agree to a five-year contract with defensive end Jerry Hughes.
March 8 -- Agree to a five-year contract with running back LeSean McCoy.
March 5 -- Exercise exclusive rights by tendering offers to wide receiver Justin Brown, defensive tackle Corbin Bryant and wide receiver Chris Hogan.
March 4 -- Agree to terms with the Minnesota Vikings to acquire quarterback Matt Cassel and an undisclosed draft pick in exchange for undisclosed draft picks.
March 3 -- Agree with the Philadelphia Eagles to acquire running back LeSean McCoy from the Philadelphia Eagles in exchange linebacker Kiki Alonso.
Feb. 17 -- Release linebacker Keith Rivers.
Feb. 9 -- Sign guard Richie Incognito
Feb. 3 -- Claim wide receiver Justin Brown.
Jan. 26 -- Add to the coaching staff Michael Hamlin (Special Teams Quality Control), Aaron Kromer (Offensive Line), Sanjay Lal (Wide Receivers), Anthony Lynn (Assistant HC/Running Backs), D’Anton Lynn (Defensive Assistant) and Chris Palmer (Senior Offensive Assistant).
Jan. 19 -- Name David Lee quarterbacks coach.
Jan. 15 -- Name Dennis Thurman as defensive coordinator. Add to the coaching staff Bobby April III (Linebackers), Karl Dunbar (Defensive Line), Tim McDonald (Defensive Backs), Jason Oszvart (Strength and Conditioning Assistant), Eric Smith (Special Teams Assistant), Tony Sparano, Jr. (Tight Ends) and Jeff Weeks (Assistant Defensive Line).
Jan. 13 -- Name Greg Roman as offensive coordinator. Terminate the contract of defensive coordinator Jim Schwartz.
Jan. 12 -- Name Rex Ryan 18th head coach in franchise history.
Dec. 31 -- Head coach Doug Marrone executes option to invalidate contract.
Dec. 29 -- Quarterback Kyle Orton announces his retirement.
Source - BuffaloBills.com and News staff reports