I've always had the impression that Stevens has a major say in team personnel. In fact, I've seen Ainge quoted as saying he, Stevens and Wyc share in personnel decisions. Perhaps it's Stevens who wants only bigs who can play on the perimeter. That really hurts them inside. Why Ainge drafted Williams is a puzzle.
The Celtics to me are too perimeter oriented to be a Championship team. That makes them vulnerable in the paint. The previous Championship teams had much better balance. This team lacks an inside game. When this team is at their best, they penetrate with lots of ball distribution, like the old Celtics teams. At their worst, they sit on the perimeter, and it's bombs away.
By the way, I hope Danny is OK and recuperating well. I understand he had a mild heart attack.