If Edelman is healthy this year (and he should play less, which means fewer hits on his body, which means he should be more effective when he IS in the game), the depth chart goes from:
Byrd
Meyers
Harry
Edelman (beat up)
Gunner
TE Izzo
To:
Agholor
Bourne
Byrd
Meyers
Edelman
TE Smith
Byrd or Meyers will no longer be matched up against the other team's CB1. They can torch CB3s or CB4s. Teams will actually have to pay attention to the TE position now. The OL is rock solid. Harris for a full year at RB.
At this point, the offense is HUGELY improved. Like...night and day. Except for one thing: QB. Ugh. Kind of a big piece of the puzzle. I will pass out from joy if they manage to trade up and get Lance, but even at this point if they somehow got Mac Jones that would be a passing improvement over Cam.
And the defense.....
Improvements on the DL (Godcheax, Anderson, and Judon), LB (return of Hightower), and DB (Mills and the return of Chung). Again, should be significantly improved. This team is in excellent shape but for the QB position. And they haven't even TOUCHED the draft yet. Now they can draft for ANYTHING they want because their needs are basically all squared away.
EDIT: I also didn't realize Byrd is a FA. Still...the WR position and pass-catching corps is much improved anyway.