Reliford began umpiring in the minor leagues in 1982, eventually reaching the Triple-A American Association.

In Game 2 of the 2000 World Series, Reliford was the home plate umpire when Mike Piazza of the New York Mets had his bat shatter and fly towards the pitcher's mound on a foul ball.

Roger Clemens of the New York Yankees fired the sawed-off piece of the bat toward Piazza, causing both benches to empty and reigniting the controversy that had begun the previous July, when Clemens had hit Piazza in the head with a pitch during an interleague game at Yankee Stadium.

On September 3, 2008, Reliford was the crew chief for the first major league game in history to use instant replay on a boundary home run call.

After a conversation with the other umpires, Reliford agreed to the replay and after a brief review upheld the initial home run call.