Dempsey made his major league debut late in the
1969 season for the division winning Twins managed by
Billy Martin, however he didn't qualify for the postseason roster. During his tenure with the Yankees, he served as a reserve catcher to
Thurman Munson, and received tutoring from Yankees coach and former catching standout
Jim Hegan. After three and a half seasons with the Yankees, the
Baltimore Orioles acquired Dempsey along with
Scott McGregor,
Tippy Martinez,
Rudy May, and
Dave Pagan for
Ken Holtzman,
Doyle Alexander,
Elrod Hendricks,
Grant Jackson, and
Jimmy Freeman at the
trade deadline on 15 June 1976. He, McGregor and Martinez became part of a nucleus that enabled the Orioles to continue as perennial contenders for the next decade. For the next ten and a half seasons, Dempsey was the Orioles' starting catcher. He became known for his exceptional ability to handle pitching staffs, his strong throwing arm, and for his agility behind
home plate. In the
1979 World Series, the Orioles won three of the first four games against the
Pittsburgh Pirates and seemed to be on the verge of winning the championship, when the Pirates, led by
Willie Stargell, rebounded to win the final three games. It was one of Dempsey's greatest disappointments of his playing career. In
1983, the Orioles won the
American League Eastern Division pennant, then defeated the
Chicago White Sox in the
1983 American League Championship Series, before winning the
1983 World Series against the
Philadelphia Phillies. Dempsey posted a .385
batting average along with a .923
slugging percentage in the five-game series, and won the
World Series Most Valuable Player Award, one of six catchers to have won the award. In
1987, Dempsey became a free agent and signed a contract to play for the Cleveland Indians. After only one season with the Indians, he became a free agent once again and signed with the Los Angeles Dodgers, where he would be a member of another
World Series-winning team in
1988, this time as a backup catcher to
Mike Scioscia. After three seasons with the Dodgers, he played one season with the
Milwaukee Brewers, before returning to the Baltimore Orioles for his final season in
1992. His sense of humor during his playing career was renowned, and he was famous for his "rain delay theatre" performances, in which he emerged from the
dugout in stockinged feet onto the tarpaulin covering the
infield during a rain delay and pantomimed hitting an
inside-the-park home run, climaxed by his sliding into home plate on his belly on the wet tarp, all to the raucous delight of the soggy fans. He sometimes did this while wearing a pair of underpants over his uniform, making fun of teammate
Jim Palmer's famous advertisements for Jockey brand briefs. ==Career statistics==