Listed as 6 feet (1.8 m) tall and 200 pounds (91 kg), he was known more for his fielding than his hitting, teaming up with Cleveland shortstop Lou Boudreau for a great double play combination in the early 1940s.

[3] Mack was selected to the 1940 American League All-Star team and pinch hit for starting second baseman Joe Gordon in the eighth inning.

Mack struck out against Larry French of the Cubs and handled no chances in the field as the AL bowed, 4–0, at Sportsman's Park.

He saved Bob Feller's 1940 opening day no-hitter with a diving stop on the final out.

[4] It was one of many deals orchestrated by Veeck, but in it Cleveland obtained pitcher Gene Bearden, who would pitch the Tribe to the 1948 pennant as a rookie.