19. Babe Ruth

Yeah, this guy.

While the world remembers Babe Ruth as the quintessential Yankee, his legend was forged on the mound in Boston. Debuting in 1914, "The Bambino" first established himself as the premier left-handed pitcher in the American League. By 1915, he was an 18-game winner with a 2.44 ERA, a vital cog in a rotation that delivered a World Series title. 

The 1916 season was Ruth’s masterpiece as a hurler. Long before the Cy Young Award existed, Ruth authored a "Category 6" proxy season, going 23–12 with a league-leading 1.75 ERA. He was the undisputed ace of the 1916 World Series champions, throwing a 14-inning complete-game masterpiece in Game 2. Between 1915 and 1918, Ruth was the engine behind three World Series titles for Boston, recording a staggering 0.87 ERA across 31 postseason innings—a high-leverage performance that remains one of the greatest in October history.

By 1918, the "Two-Way Experiment" was in full flight. Ruth transitioned into the outfield while still making 20 starts on the mound, leading the league in Home Runs (11) and Slugging (.555). In 1919, he shattered the baseball world's concept of "Category 3" Era Dominance. He blasted 29 home runs—breaking a 20-year-old record—while simultaneously leading the league in Runs (103), RBIs (113), OBP (.456), and bWAR (9.1). It was a statistical takeover of a sport that had never seen a player dominate both the rubber and the batter's box with such ferocity.

The franchise's trajectory changed forever in late 1919 when owner Harry Frazee, seeking to finance his Broadway interests, sold Ruth to the New York Yankees for $100,000. This "Transaction of Infamy" birthed "The Curse of the Bambino," an 86-year championship drought that defined the Red Sox identity for nearly a century. Ruth left Boston having already achieved a Hall of Fame trajectory as a pitcher, only to become the greatest hitter in history elsewhere.

Ruth was an inaugural member of the Baseball Hall of Fame in 1936 and a charter inductee into the Red Sox Hall of Fame.