Why do you view Hall as having "leadership" skills? Edmonton made and won a round in the playoffs the year after he left - something they never did with him. Hall has admitted to not working as hard as other elite players during the offseason and admitted to Shero he was playing at about 50% of his capabilities after the 16-17 season. IMO a consistent effort is a bare necessity for a leader.
I'm not sure that 50% comment is accurate, but regardless he obviously made a change as he matured as evidenced by his MVP season. Perhaps he wasn't ready to be a leader earlier in his career, but maybe he is now.