Well, we're about to get another 16 games to add to the case. This year will fall onto Kelly's ability to call the offense, can receivers stay healthy and effective while running the right routes, will the TE's be incorporated into the passing game to the point that the team uncovers its own Kelce, will the running game be effective enough to keep defenses honest, and finally.....will the OL mesh in 2020 with its current personnel. As for Watson, he'll be as effective as the offense around him.
The ol if healthy should be very much improved. You're right about DW4 Being as good as the offense around him. He certainly isn't capable of carrying an offense right now.