Complex sentence: He coached at the high school level in New York and at the college level at Connecticut, Maryland and Tennessee before landing a professional football assistant coaching job with the American Football League's Denver Broncos in 1967.
Split into simpler sentences: He coached at the high school level in New York. He then coached at the college level at Connecticut, Maryland and Tennessee before landing a professional football assistant coaching job with the American Football League's Denver Broncos in 1967.