After graduating from Lowell in 1950, Ed attended the University of California at Berkeley, where he played baseball for two seasons.

Mayer was called up by the Cubs, and he made his major league debut at Wrigley Field against the New York Giants on September 15, 1957.

Ed pitched five innings, leaving with the score 5–3 in favor of the Giants after Hank Sauer belted a three-run homer in the fifth.

Instead, the Cubs scored four more runs, Don Elston racked up the 7–6 win in relief, and Turk Lown got a save.

On June 5, 1958, in his final big league appearance against the Philadelphia Phillies, he faced two batters, hitting the first and yielding a three-run double in what became a 7–6 loss.