What the data shows is that no matter how big a celebrity's bankability is, its nowhere near the bankability of when they team up with the right people. Not just any people, the RIGHT people. Scorsese and DiCaprio, Spielberg and Tom Hanks...these divine combinations along with the other smaller relationships within a production are what yield results whose sum is greater than its parts.
Which goes to show you, even if you are a celebrity, you are NOT directly responsible for your own success, no matter how big you are. Success is what happens when talented people team up with other talented people who thus enhance each other's talents.
Its about relationships, but not just any relationships, the RIGHT relationships. One of those universal truths I'd say you could probably apply to more than just movies.