In 37 career games in Buffalo, Watkins had 153 catches and 17 touchdowns, although he missed 11 matches over the last two seasons.
In exchange for Watkins, the Bills received E.J. Gaines, a cornerback who is gearing up for his third season in the NFL. Now L.A. has their No. 1 and 2 receivers from last season, granted Watkins only played eight games a year ago as he dealt with injuries.
Watkins's future in Buffalo had already been in question after the Bills declined in May to pick up his fifth-year option.
The Rams need playmakers for an offense that finished last in the National Football League over the past two seasons.
The trade gives Buffalo two first and second round draft picks in 2018, ammunition for a front office that has been non-committal on starting quarterback Tyrod Taylor. However, he's been nicked by injuries throughout his career and only appeared in eight games last season. When he is healthy he is a threat to be reckoned with. Darby, who finished second in defensive rookie of the year voting in 2015, had started 29 games over the past two seasons. Matthews has 225 catches for 2,673 and 19 touchdowns in three seasons.
He'll be an unrestricted free agent next year unless the Rams slap the franchise tag on him.
The three picks leave Buffalo's front office with enormous flexibility entering the 2018 draft next spring.