[1] He started his professional career with Class C Aberdeen Pheasants (1963–1964), and won the International League Pitcher of the Year Award while playing for the Rochester Red Wings in 1967, gaining a promotion to Baltimore late in the season.

[1] On May 6, 1968, Leonhard took a no-hitter into the seventh inning before Detroit Tigers outfielder Jim Northrup broke it up with a single after two outs.

[4] On May 30, 1968, he shutout the Chicago White Sox at Comiskey Park, 5–0, giving up just two singles to Luis Aparicio (4th inning) and Tommy McCraw (7th).

[3] He also pitched with the Puerto Rican team in the 1971 Caribbean Series and for Triple-A Salt Lake City Angels in 1973.

[citation needed] In a six-season major league career, Leonhard played in 117 games, accumulating a 16–14 win–loss record along with a 3.15 earned run average including; 29 starts, seven complete games, four shutouts and five saves, giving up 118 earned runs on 287 hits and 150 walks while striking out 146 in 337.0 innings.

She had been his girlfriend in high school, but they stopped dating initially when he went to college; however, their relationship started again when they saw each other at an alumni football game.