The 6 ft 3 in (1.91 m), 205 lb (93 kg) Mickelson, a right-handed hitting first baseman, had an 11-season career, all but 18 games of it spent in minor league baseball.

[2] Mickelson collected only one hit and two bases on balls in 12 plate appearances over five games, however, and returned to the minor leagues for almost three full seasons.

In the third inning of the Browns' final game on Sunday, September 27, at Busch Stadium, facing the Chicago White Sox, Johnny Groth doubled off Billy Pierce with two out.

[3] But Chicago came back to tie the game in the eighth, sent the contest to extra innings, and won it 2–1 with a run in the top of the 11th.

The RBI single was Mickelson's last big-league hit; he went hitless for the rest of that game,[3] and then was 0-for-12 in his last Major League stint with the 1957 Cubs.