He was the first person in UC Riverside history to both receive an athletic scholarship and be selected in the MLB draft,[4][5] 401st overall in the 18th round by the Cleveland Indians in 1968.

He was traded by the Indians to the Blue Jays for designated hitter Rico Carty, and reacquired in the same off-season for utility infielder Héctor Torres.

[9] Lowenstein hit an extra inning walk-off home run for the Baltimore Orioles to win Game 1 of the 1979 American League playoffs against the California Angels.

While sliding into second base in an attempt to extend a game-tying single, he was accidentally hit on the back of his head by a ball thrown by first baseman Jeff Newman who was the cut-off man on the play.

"[8] Lowenstein was an announcer for Oriole television broadcasts on Home Team Sports for eleven seasons, working as an analyst with Mel Proctor.