ANAHEIM, Calif. — On its surface, the story does not make sense. Kawhi Leonard needed someone to drive him? Leonard, a 6-foot-7, do-everything talent for San Diego State whom his coaching staff and teammates hail as the Aztecs’ most tireless worker and the man behind the wheel of their historic N.C.A.A. tournament journey, could not drive himself? Not exactly. But in what has become a comical subplot to the tale of a player who is one of the top N.B.A. prospects in the tournament, Leonard’s basketball career was once threatened by an inability to secure transportation.