If you search back through the history of the National Hockey League, there are a number of teams that found glory after gaining one player who made that one key difference. The Edmonton Oilers brought over Wayne Gretzky, the New York Rangers acquired Mark Messier, the New Jersey Devils drafted Martin Brodeur, the list goes on and on and on.
For the St. Louis Blues, you can make an argument that their greatest player of all time would be Brett Hull, and deservingly so. But, can there be one more player that, had he never emerged into his role on the sole Stanley Cup victory in this franchise's long-standing history, rival Hull?