Well, Armanti is listed 2nd behind Smitty, and Pilares is 3rd behind LaFell.
So, I would read that as Armanti being forth. Unless they consider them vastly different WR positions.
All the guys will get some opportunities .
With the way Rivera seems to think, the question seems to be, schematically, which WR provides the most of what they are looking to do (whatever it is they're looking to do). Not sure if the game plan will change fit what Pilares, Edwards, or Tutu do best if they do anything "best", instead of trying to see if either of them can do what the offense has been doing.
Naanee was recently catching a lot of shorter passes underneath, the one running in motion, probably setting up in the slot (I wasn't looking). Not sure that's either Pilares' or Tutu's game as they seem to be better at stretching the defense (based on their pasts), but maybe Edwards is better suited for underneath passes, so he'll get the lion's share of snaps as #3.