If you're trying to mirror the Pats success then you don't pay a slot receiver $13M/year. Edelman's contract averages $4.25M/yr with $8M guaranteed. Landry maybe the best, but the Team needs to find a suitable replacement at lower cost.
I'm not sure this is a fair comparison. Julian Edelman is a fine slot receiver in NE, but his ability to get open is helped by the fact that teams always had to account for multiple weapons. Even though the Pats rarely had a top notch boundary WR, you still had to account for them, Gronk, and the running backs. Look over their stats and its a pretty decent spreading of throws. Edelman dominates because McDaniels gets him in space and Brady has the accuracy to get him YAC opportunities.
Landry is not and has not been catching passes from a HOF QB. He also has younger WRs who cannot get on the field and run incorrect routes. He's never had a good TE to draw defenders in the middle of the field. He's pretty much been asked to do it all. If Miami is committing to Tannehill for 2018 then give him the guy he's had the best rapport with.
I doubt Landry gets $13 million per year on the open market, but Miami can give him a lot of guaranteed money while reducing his annual cap hit for the time being. I think the brass has learned very quickly that Parker will not be the alpha they hoped for. You have to keep the guys who produce, and right now its Landry and Stills.