On the plus side this team hasn't had this much talent at WR probably since Clayton and Duper.
I don't know what you are seeing. Unless Parker has a breakout season, this is the worst WR corps MIA has had since probably '09 (Ginn/Bess/Camarillo)... and I would happily take '09 Bess over any WR currently under contract in MIA.
Landry for Amendola is unquestionably a downgrade, so at a very minimum there was more talent at WR last year. I'd also say that the '05-'06 teams with Chris Chambers/Marty Booker/Wes Welker had significantly more talent, as did the '10-'11 teams with Brandon Marshall/Davone Bess/Brian Hartline, and the '15 team (Landry/Parker/Stills/Rishard Matthews).
If Parker plays in '18 as he did in '17, there is only one respectable WR on the team (Stills). No other WR on the Dolphins should even be a starter.