Yes, it seems Horford is the only one who is an automatic bigs starter.
A lot could depend on the preseason. Is Olynyk back 100%? Maybe Brad will like the idea of Amir with Olynyk together for a second unit and then a Jerebko gets his chance to start. Or Zeller!
My opinion is that Amir will get the nod. He's just too darn good and a proven veteran. I think Olynyk is the next clear cut choice after Amir. Amir Johnson could come in as Horford's replacement. Amir and Al are the best we have for center defense. Brad might want one of them on the floor for most of the games. I hope Brad doesn't experiment so much this time like he did after the Rondo trade. The Brandan Wright era was very painful.
I hope Coach Stevens goes with four guys with probably three of them getting most of the minutes, like how Isaiah, Avery and Marcus tend to gobble up most of the guard minutes. Three amigos.