Former big league pitcher turned pitching coach Mel Queen passed away today at the age of 69. His cause of death is not known.

Queen spent a quarter century with the Toronto Blue Jays serving in various capacities. From 1996 to 1999, he was the team’s pitching coach.

But Queen is perhaps best known for turning Roy Halladay into the most feared pitcher on the planet. When the Jays sent Halladay down to A ball a decade ago, it was Queen who changed both his mechanics and his mental approach.

Last year, Tom Verducci did a cover story on Halladay last year for Sports Illustrated. In the piece, Verducci cited Queen’s first conversation with Halladay after he had been sent down. Queen ripped into Halladay and said, “Look at you! You’re stupid! You’re an idiot with no baseball intelligence and no guts! You’re a pussy!” (H/T ‘Duk at Yahoo! Sports)

Let’s just say that Queen wasn’t there to massage Halladay’s ego. Well, since Halladay returned from his demotion, he’s won 161 big league games, tossed nearly 60 complete games, won two Cy Young Awards and threw a perfect game and a no-hitter in the same year. None of this would have been possible without Queen. He turned Halladay into a future Hall of Famer.