Six-time All-Star pitcher Sam McDowell died Monday at 84.

The cause of death is unknown. KDKA first reported McDowell’s death.

McDowell pitched in the big leagues for 15 seasons, spending 11 of them with the then-Cleveland Indians, parts of two seasons with the San Francisco Giants, parts of two with the New York Yankees and his final season with the Pittsburgh Pirates.

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American baseball pitcher Sam McDowell of the Cleveland Indians poses at Municipal Stadium in Cleveland in July 1969. (UPI/Bettmann Archive/Getty Images)

McDowell, nicknamed "Sudden Sam," won the American League ERA title in 1965 with a dazzling 2.18 ERA and made the first of his six All-Star Games that season. In his career, McDowell had a 141-134 record with a 3.17 ERA in 425 games.

The Pittsburgh native is in the Guardians Hall of Fame. McDowell made his MLB debut at 18 but was out of baseball by 32 in 1975 because of alcohol abuse.

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Sam McDowell attends the 22nd annual Going to Bat for B.A.T. event at The New York Marriott Marquis on Jan. 25, 2011, in New York City. (Dario Cantatore/Getty Images)

"I was the biggest, most hopeless and most violent drunk in baseball," McDowell told the New York Post in 2001. He recalled jumping off of hotel balconies into swimming pools.

In that same interview, McDowell said he had lost his family and career to alcohol. He went to rehab in 1978 and turned things around. He went back to college and became a licensed therapist in sports psychology and addictions.

Former Cleveland Indians player Sam McDowell attends the Hall of Fame induction ceremony before the game against the Oakland Athletics at Progressive Field in Cleveland, Ohio, on July 30, 2016. (Jason Miller/Getty Images)

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McDowell then returned to baseball, working for the Toronto Blue Jays and Texas Rangers. From 1987-2016, he served as an addiction and recovery consultant for the Baseball Assistance Team.

"I truly believe with all my heart, the greatest thing that ever happened to me was that I was an alcoholic and found out about it," McDowell said. "Had I never known and had not been thrown out of baseball, I would not have the great life I have now. I would not have the education. I would not have learned how to live and love. Every day is a kick."