As a junior and senior Mosier was the school's starting quarterback and posted an 18-0 record and was named All-State in 1965.
He set school records with 37 receptions for 495 yards and four touchdowns and was named the Big Eight Conference Newcomer of the Year.
[4] Mosier was selected in the sixth round of the 1970 NFL by the Denver Broncos.
[6] He played in all 14 of the team's games with one reception of 53 yards against the New York Jets.
[7] Mosier was traded to the Buffalo Bills for a draft pick in 1973, but was cut during training camp.