Not moving your WRs around makes it more difficult for the them to be successful. Chase is moved around. Jefferson is moved around. Hell, Brian Thomas is moved around. Nabers is moved around. Every top WR should be moved around so that the opposing team has a tough time scheming how to take that WR out of the game. So, it is a schematic decision and the decision to leave a WR in a stagnant role is one that makes it more difficult for the WR.
According to RotoWire:
Harrison has lined up at right outside 41% of the time, left outside 39.5%, right slot 18%, left slot 16%, right tight 1 play, left tight 1 play.
The other rookies:
Thomas has lined up at right outside 38% of the time, left outside 35%, right slot 27%, left slot 28%, right tight 1 play, left tight 1 play.
Nabers has lined up at right outside 34.5%, left outside 34.5%, right slot 23%, left slot 17%, right tight 8 plays, left tight 5 plays.
Veterans:
Chase has lined up at right outside 31% of the time, left outside 36%, right slot 24%, left slot 26%, right tight 4 plays, left tight 2 plays.
Jefferson has lined up at right outside 34% of the time, left outside 44%, right slot 22%, left slot 26%, right tight 0 plays, left tight 4 plays.
So while Harrison has been in the slot a
little less than the others, it's not as though he's not being moved around.