Was thinking about this the other day. Unless one of your guys 2-4 is a primary playmaker type, the potency of your offense is really going to depend a great deal on the quality of players you have at the 1 and the 5. The Celts certainly do not have a capable primary playmaker on the wing.
The 1-5 pick and roll is a bread and butter player for a modern NBA offense. Especially in the regular season. Also, teams typically rely on their 1 to hold down primary playmaking duties, and the 5 is crucial for setting picks, creating pressure on the rim by running to the rim / catching lob, or spacing the floor via pick-and-pop.
So what do the Celts have?
Timelord has come a long way in a short time, but I'm not sure where he ranks overall in the league as a starting center.
Schroder is a MLE type player for a reason. He's really playing out of his depth as a starting point guard / lead shot-creator.
Where do you think those two rank leaguewide among starters at their position?
Just as a starting point for the discussion -- according to 538's RAPTOR, this is where these two rank at their position:
Dennis Schroder -- 42nd
Rob Williams -- 18th
Note, however, these lists include backups.
This seems about right to me, though. I think I would probably rank Rob higher. It's a little hard to understand why he comes in that low. For this season, at least, it's not an issue of minutes.
My instinct is that Rob is probably somewhere around the 10th best starting center in the league, though it's debatable.