Hall is best known as a member of the Baltimore Orioles dynasty that won four American League pennants and two World Series championships between 1966 and 1971.

[8] Hall was heavily scouted by major league teams while playing at Swarthmore College, ultimately choosing to sign with Branch Rickey and the Pittsburgh, Pirates.

After short trials during that season and in 1953, he spent all of 1954 on the Pittsburgh roster, and started 84 of the club's 154 games: 32 in left field, 43 in center, and nine in right.

[9] The following year, 1955, he began his transition to the pitcher's mound, going 12–5 with 16 complete games and a 2.24 earned run average for the Lincoln Chiefs of the Western League.

[13][9] He became exclusively a pitcher in 1957[14] but, battling a sore arm, he spent most of the season with Triple-A Columbus, then all of 1958 on the sidelines, with hepatitis.

[15][4] He returned to action in 1959, and at age 28 had a breakthrough season in the Triple-A Pacific Coast League with the Salt Lake City Bees, winning 18 games,[10] earning an MVP award[16] and September recall to Pittsburgh.

[18] As the 1961 season was about to begin, Hall was acquired by the Orioles along with Dick Williams for Chuck Essegian and Jerry Walker on April 12.

[2] His Baltimore tenure was interrupted by two years (1967–1968) back in the National League as a key member of the Philadelphia Phillies' bullpen.

[17][3] After a stellar 1967 season (ten wins, nine saves, and a 2.20 ERA), he slumped in 1968,[9] and when the Phillies released him on October 29,[17] the Orioles signed him as a free agent in 1969 after a spring training trial.

Hall rebounded to win 21 games and save ten others for three consecutive pennant-winning Oriole teams through 1971.

[14] The Pirates sent Hall to Mexico for winter baseball, and he met his future wife Maria Elena Nieto there in 1955.