Thomas was selected in the fifth round of the 1975 NFL draft by the Washington Redskins. In his rookie season, he rushed for 919 yards and was named the Associated Press Offensive Rookie of the Year. The following season in 1976, Washington returned to the playoffs as the wild card team; Thomas ran for over 1,100 yards and went to the Pro Bowl.
In his fourth season in 1978 under first-year head coach Jack Pardee, the Redskins won their first six games. Thomas injured his ankle in that sixth game and sat out the next three games. Washington lost eight of the last ten games to finish at 8–8 (.500) and missed the playoffs.
Thomas was traded to the San Diego Chargers in May 1979.[1][2] After playing two seasons, he was waived by the Chargers in September 1981.[3]