I like Speights as a player, and he would be a good mesh with Rondo in the future. I agree with you on putting him in the 3rd string -
_________(defensive minded center), Jermaine, Speights
That sounds really good center-wise. He can play both the 4 and 5, and can somewhat stretch the floor. Speights would play improved D thanks to KG. But finding a Defensive center is our top priority right now. Once we find a Perkins type player, Speights would be on the top 5 of my list if Ainge were to search for more bigs.