Prochaska went on to be an assistant coach, often serving under Chuck Knox with multiple NFL teams, and in 1961 briefly served as interim head coach of the St. Louis Cardinals. He coached under Knox with the Los Angeles Rams, Buffalo Bills, and Seattle Seahawks. After Pop Ivy resigned late in the season, Prochaska shared head coaching duties with fellow assistant coaches Chuck Drulis and Ray Willsey. Under the trio's guidance, the team won its last two games.
