At the intersection of the Venn diagram of ways to achieve greatness, Shohei Ohtani makes for a population of one.
There have been 701 games in which a player hit three home runs, postseason included. There have been 10,259 games in which a pitcher struck out 10 batters or more. Those sets of greatness had never intersected, nor would anybody expect them to, until Ohtani rewired our minds to what is possible.
