Epstein was dubbed Superjew by rival manager Rocky Bridges after he led the California League in batting and home runs in 1965, and was The Sporting News Minor League Player of the Year in 1966 when he won International League MVP honors at Rochester (.309, 29 HR, 102 RBI). The burly, lefthanded slugger arrived at spring training in 1967 as baseball’s most-heralded prospect, but after the Orioles tried in vain to convert him to the outfield (they already had Boog Powell at first base), they demoted him to Rochester again. The outspoken Epstein refused to report, going home to California instead, and did not play again until the end of May, when he was traded to the Senators with Frank Bertaina for Pete Richert. Later that season, in his first at-bat against the Orioles, Epstein hit a grand slam.
Epstein was a capable power hitter in the ML, but never hit quite well enough to offset his frequent strikeouts, poor defense, and big mouth. He hit .278 with 30 HR for the Senators in 1968, but slipped to .256 with 20 HR in 1970 and was one of four players traded to Oakland for Darold Knowles before the 1971 season. With the A’s, Epstein hit .270 with 26 HR in 1972, but was 0-for-16 in the WS and was traded back to the Rangers (formerly the Senators) for relief pitcher Horacio Pina in November. He played only 27 games with Texas in 1973, then was traded to the Angels, and after hitting .161 in 18 games for California in 1974 Epstein was out of the ML for good.