South High was the beginning of Dienoff's athletic career. He participated in football and basketball and ran track, setting a new state record in the mile run of 4:29. He entered Syracuse on an athletic scholarship and quickly finished first in the National Freshman Cross Country Championships. He returned to Akron and completed in track, baseball and basketball. In 1937 he took over at Garfield High where he coached baseball, golf, swimming and tack. During his 20-year stint, Dienoff's baseball team won the City Championship 10 times, the District Title seven times and two regional championships.