He was the #1 pick of the 1980 NFL Draft by the Detroit Lions where he played from 1980 to 1984. During his NFL career Sims was named Offensive Rookie of the Year and UP NFL-NFC Rookie of the Year in 1980. He was also named a second-team All-Pro in 1980 and a first-team All-Pro in 1981. Sims was selected to the Pro Bowl in 1980, 1981, and 1982. He was forced to retire after four seasons in the NFL due to a knee injury. He lost his wealth through failed business ventures and filed bankruptcy in 1990. In 1995 Sims sold his Heisman Trophy to businessman Bob White for $50,000.