Any WR is only as good as their production. While I don't like to ever agree with LKP, he's right, based on current production, Marvin Jones is no worse of a receiver than AJ Green.
Green has a much better chance to bounce back to elite status, as Jones has never been elite, but you can't argue that one is worse off that the other at this point.
Lots of elite players have declined. Last year and the year before were down years for Green. There is no suggestion that I can see that AJ is still an elite receiver. There is no suggestion that Jones has ever been elite.