Byars was a tailback at Ohio State University from 1982 to 1985.
In 1984, he was runner-up for the Heisman Trophy (to Doug Flutie) after a season where he gained an OSU record 2,441 all-purpose yards, including a then-school record 1,764 rushing yards and 22 touchdowns. He was a unanimous first-team All-America selection, and voted the Big Ten Conference Most Valuable Player.
1984 featured a game against Illinois in which Byars led a come-back from a 24-0 deficit, rushing for 274 yards and five touchdowns, the last with 36 seconds remaining in the game. On his 4th touchdown run, going for 67 yards, he famously lost his left shoe at the Illini 40 but never broke stride.
Byars was a preseason favorite for the 1985 Heisman, but fractured the bone in his right foot near the little toe in preseason practice. He missed the first five games of the 1985 season, and returned too early. He reinjured the broken bone in his second game back and missed the remander of the regular season. He attempted to return for the Citrus Bowl game on December 28, but reinjured his foot again in the second Ohio State offensive series of the game. Many observers note that throughout the remainder of his football career Byars was never as dominant a player as he had been in 1984.
Despite losing almost his entire senior year, Byars finished his college career at Ohio State with 4,369 total yards, 3,200 rushing yards, and 50 touchdowns. His 50 touchdowns remain the second most in school history.
As a professional, he played fullback and tight end for the Philadelphia Eagles (1986-1992), Miami Dolphins (1993-1996), New England Patriots (1996-1997), and the New York Jets (1998). Byars was selected to the Pro Bowl in 1993.
A superb rusher, blocker, and pass receiver, Byars was a vital contributor for every team he played on. In 1988 he rushed for 517 yards, recorded 71 receptions(ranking him 9th in the NFL), and scored 10 touchdowns. In the Eagles 20-12 loss to the Chicago Bears in the postseason, he rushed for 34 yards and caught 9 passes for 103 yards. In 1990, he recorded 81 receptions for 819 yards, the third most receptions in the NFL, rushed for 141 yards, and even completed 4 of 4 passes for 53 yards and 4 touchdowns. In the 1996 season, Byars made his first and only championship appearance, playing with the Patriots in Super Bowl XXXI. His team lost the game 35-21, but the 33-year old Byars had a good performance in it, catching 4 passes for 42 yards and a touchdown.
In his 13 seasons, Byars rushed for 3,109 yards, caught 610 passes for 5,661 yards, returned 5 kickoffs for 94 yards, and completed 6 of 13 passes for 119 yards and 6 touchdowns, with 1 interception. He also scored 54 touchdowns (23 rushing and 31 receiving)