I don't think the Celts should actually be that worried about the lack of size inside.
I don't think there's a solution to that problem that isn't going to cause issues elsewhere.
If anything I think they should be concerned with upgrading shooting on the bench without compromising too much on defense.
Great analysis. Let's not screw up great chemistry again.
It's a tough problem because I do agree with the OP - we need an upgrade in the post. I think, to win our next title, we need a dominant post player for this group. Either that, or Robert Williams makes big improvements over the next year and we add some knock-down shooters and go with a quick, scrambling defense and overwhelming offensive firepower. Still, no rebounds, no rings.
As for Smart, he is our Draymond Green playing at guard instead of post. He is a difference maker and it seems most title teams have an intangible player like him.