You've been playing too much madden. They just signed Alec Peirce to a huge contract, they just signed Jones to a big contract, Jonathan Taylor will need extended... It's a balancing act, tough choices must be made, at a $29m cap hit, they didn't want to be the Bengals and have 100m tied up in WR with no defense.
We've had to watch guys walk over the years for the very same reason. Every year the super bowl winning team loses a bunch of players because they can't afford to keep them all.
So again, it wasn't for lack of production, strictly a money issue