After retiring from coaching, Holcomb was the athletic director at Northwestern University (1956–1966) and later the general manager of Major League Baseball's Chicago White Sox (1971–1973).

This team was dominated by defense, only allowing their opponents to score in double digits twice; A 34–12 win over Bradley University and a 35–0 blow out loss to Arkansas A&M.

Holcomb’s Purdue teams are, perhaps, best remembered for ending Notre Dame's 39-game unbeaten streak when his Boilermakers defeated the Irish, 28–14, in the second game of the 1950 season.

After the Mustangs folded following the 1968 season, Holcomb was reassigned to the Chicago White Sox, another of the Allyn brothers' business entities, as its public relations director.

With the White Sox's record at 49–87 and en route to a franchise-worst 56–106 finish,[2] Holcomb was promoted to replace Ed Short as general manager on September 1, 1970.

[3] He immediately began overhauling the ball club that month with the dismissal of Don Gutteridge on the 2nd and the hiring of Chuck Tanner and Roland Hemond from the California Angels as manager and director of player personnel respectively two days later on the 4th.