Other teams do this though like Phoenix although I don't think Ainge is doing it as intentionally as that. Ainge would rather take the bpa then focusing on pg's where Phoenix focuses on pg's too much. They had to sell us Isaiah cheap because they had too many.
Ainge to me is smarter than that. He got Isaiah and drafted Marcus mainly because they were talented players that give us options and fit what we are trying to do at the same time.
He took the bpa, he also filled needs, and gave us the best options going forward that way. They also can play together in some way and compliment each other.