It's a move that doesn't come as much of a surprise, as Rivers barely saw the field in the second half of last season and wasn't expected to have a role at linebacker next season.
The transaction, however, is a chance to circle back on how the Bills plan to stock their defense under Rex Ryan's scheme next season. The best indicators are how Ryan used his personnel with the New York Jets last season and how his protege, Mike Pettine, used players when he implemented Ryan's scheme with the Bills in 2013.
Fitting the puzzle pieces into place isn't an exact science, as some players are capable of playing more than one role. There is also the issue of base versus sub defense. What follows is how Ryan figures to align his base defense, but his sub defense is becoming equally important, as teams are using it for 50 percent or more of their snaps in today's NFL.
Given that disclaimer, here is a look at how the Bills figure to construct their defense for next season:
"Mike" and "Will" linebackers
Responsibilities: Varied, but usually aligned 4-6 yards off the line of scrimmage. Duties include taking on offensive guards in running game, protecting middle of the field in zone coverage and occasionally blitzing.
2013 Bills: Manny Lawson
2014 Jets: Calvin Pace
2015 Bills candidates: Lawson, possibly Jerry Hughes (if re-signed) or other free agent/draft pick
Responsibilities: Typically aligned as a stand-up linebacker, on or near the line of scrimmage and sometimes over the tight end. Responsibilities include jamming tight ends and slot receivers, containing outside runs, dropping into short zone coverages and pass rushing.
Defensive end/rush end
2013 Bills: Mario Williams
2014 Jets: Quinton Coples
2015 Bills candidates: Williams
Responsibilities: Most often aligned in a three-point stance as a defensive end. Responsibilities usually are limited to pass rushing and containing outside runs but can also stand up and drop into coverage on some zone-blitz-style schemes.
Responsibilities: Almost exclusively aligned as down linemen in three-point stances. Responsibilities include containing inside runs and controlling the line of scrimmage against offensive linemen ("eating up" blockers).