Timing and context is everything in sports, and changes to the game and rules and technology often render comparisons moot (how you compare between eras in a sport like tennis, for example, where players once used wooden spatulas compared with the carbon-fiber lightsabers they use now, is beyond me.) After a while, it becomes clear that these "greatest ever" debates are more about the provocations than the resolutions.

WSJ: Does Jordan Need to Be No. 1?