Having former slam-dunk champs or runner-ups as judges, should be the most ideal way for the Slam Dunk contest.
However, since this is an event under the wide spectrum of the All-Star Weekend, it's almost a mortal sin not to cast artists, legends, etc.
IMO it's fine the way it is, hindi mawawala ang subjectiveness since it's dunking. Hindi exact science, tulad nang 3-point shootout.
Pag bawalan na lang sana ang collusion between judges. Maybe put a divider there somewhere.