The missing piece probably won't play this game. McCutcheon will be the final piece in this WR room IMO. He can block, make contested catches, and has the speed and size that Stafford likes.
Robinson is IMO replacing not just Woods, but OBJ as well. Robinson can play all WR positions and he's a willing blocker. Once Jefferson returns this pass attack will be hard to stop. Once McCutcheon develops, i.e. next year, this could be the best WR room in the NFL being truly 4 deep. Tutu IMO is a situational player. He's going to have to show he can take the pounding of a 3 down WR. I think next year the WRs will be Kupp, Robinson, Jefferson, McCutcheon, and Tutu.
I meant it when I said Robinson is an upgrade to Woods and this offense was very good with Goff, Kupp and Woods. Now with Stafford, Kupp, Robinson and Jefferson, it's going to be downright dangerous.