On the eve of the World Series, Major League Baseball is mourning the death of long-time umpire Eric Cooper.

Cooper's death was announced Sunday and caused by complications from a blood clot following knee surgery earlier in the week, according to Major League Baseball. He was 52 years old.

The final series of his respected career was between the Twins and Yankees in the American League Divisional Series, which New York swept in three games.

According to the Associated Press, Cooper worked as the second base umpire during Game 3 at Target Field.

"This is a very sad day across Major League Baseball," MLB Commissioner Rob Manfred said in a statement. "Eric Cooper was a highly respected umpire, a hard worker on the field and a popular member of our staff. He also served as a key voice of the MLB Umpires Association on important issues in our game."

MLB Players' Union Chief Tony Clark called Cooper a "friendly and familiar presence" with a "passion for our game."

"His hard work, dedication and skill over nearly three decades saw him rise from the low minors to eventually becoming one of the best, most respected umpires in Major League Baseball. Players extend their deepest condolences to his family and friends," added Clark.

Cooper is a Des Moines, Iowa, native who attended Iowa State University.

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