Dennis Eckersley is one of the most revolutionary pitchers in baseball history, and a rare star who mastered two careers: first as an All-Star starter, then as the prototype for the modern dominant closer. Few players have ever reinvented themselves so completely or shaped the sport so profoundly.

Eckersley broke in as a hard-throwing starter, throwing a no-hitter in 1977 and making multiple All-Star teams. But his move to the bullpen with the A’s in the late ’80s changed baseball. He became the first closer to pair elite command with strikeout stuff, walking just 3 batters in 1990 and posting a 0.61 ERA—one of the greatest relief seasons ever.

His 1992 MVP and Cy Young season made him the symbol of late-inning dominance, and his pinpoint slider/fastball combo became a blueprint for future closers. Beyond awards, he defined the emotional drama of the 9th inning and showed how a pitcher can reinvent himself into legend.