Hi,
For the ASG, the great part of veteran managers in the game are saying (they must be right about it) that the vote calculations are quite ... "strange" (?!).
It is rather linked with the ratings and salary, obviously not with the "Role" of the player in his team which could explain why Fortune starts in the ASG when Zimmerman does rank 3rd in the votes.
And as other said right before, ASG is for fun and has no impact on the game (merch./ revenues/ GS ...). It could have been fun for you to have both of your young centers in the ASG, but strange vote calculations + no impact in the game --> don't bother yourself bro.
(out of topic : you purchased Zimmerman from a former league&division mate of mine ! And he just promoted last season, playing the same att/def scheme as I did for 3 seasons. This guy used to play inside oriented and then went to my sweet princeton/3-2. Damned bas*** ! ^^ Actually, this is the main reason why Zimmerman won't play in the ASG : he has been drafted by my rival !!! x°B )