Best has had time to prove himself. Granted it wasnt very long, but at the end of the day he failed to score in 11(?) championship games for us, add that to the fact he hasnt showed he might have the ability to do well in the PL at any point in his career, could anyone blame Hughton or anyone else for not having faith in him to get the goals to keep us up?
He'll get his chances, if he impresses in training/pre season/in substitute appearances this season then he'll earn the faith and change peoples minds. However I dont think he's good enough to do that.