Mark Buehrle of the Chicago White Sox just minutes ago pitched a perfect game against the Tampa Bay Rays. A perfect game is the ultimate in hot pitching, as it requires a pitcher to retire each and every opposing batter. Beyond pitching a no-hitter (which Buehrle had already done once in his career and which I analyzed here), the pitcher of a perfect game also allows no walks, hits no batters, has his fielders (and himself) commit no errors, etc. Buehrle's is just the 18th perfect game in major-league history.