The running back position has become an essential piece of the offensive puzzle in college football and the NFL. As football evolves, the running back position has become one of the most highly utilized positions in the passing-based structure of the modern-day game.Najee Harris and Travis Etienne headlined the talented group of running backs selected during the 2021 NFL draft. The 2022 running back class is exceptionally gifted. There's a great chance at one of the running backs on Sportskeeda top-five running backs list that could be in the Heisman Trophy race.Here's a look at Sportskeeda's preseason top-five college football running backs heading into the 2021 college football season.College Football's top-five RB's heading into the 2021-2022 seasonIowa State RB Breece Hall#1 Breece Hall, RB, Iowa StateBreece Hall is the only returning player in college football that received Heisman votes last season. Hall has put together two tremendous seasons as the Cyclones running back. The junior running back is coming off a sophomore season where he rushed for 1,572 yards and 21 touchdowns on 279 attempts.Early 2022 NFL Draft running back rankings1. Breece Hall, Iowa State2. Jerrion Ealy, Ole Miss3. Isaiah Spiller, Texas A&M4. Zonovan Knight, NC State5. Chris Rodriguez Jr. Kentuckyhttps://t.co/VmX28qLQMc— PFF College (@PFF_College) July 4, 2021Iowa State is returning both their starting quarterback and running back for the upcoming season. The Cyclones are going to lean heavily on Brock Purdy and Breece Hall to carry their team. Hall has a great chance at being in the race to win the Heisman trophy at the end of the season.#2 Kennedy Brooks, RB, OklahomaKennedy Brooks is coming off an entire season of rest. Brooks was part of the group of players in college football who opted out of the 2020 college football season.Before opting out of the 2020 college football season, Kennedy Brooks had back-to-back seasons with over 1,000 rushing yards. His freshman season remains the best year of his career at Oklahoma. Brooks rushed for 1,056 yards and 12 touchdowns on 119 attempts during his freshman year.Kentucky RB Chris Rodriguez Jr.#3 Chris Rodriguez Jr., RB, KentuckyThe Kentucky Wildcats are very rarely praised for their football team. Chris Rodriguez Jr. is heading into the 2021-2022 college football season as a top running back prospect.Chris Rodriguez Jr. will play a massive role in the Wildcats' offense this season. Rodriguez is coming off his best season at Kentucky. The Wildcats running back rushed for 785 yards and 11 touchdowns on 119 attempts during the 2020 college football season. Kentucky's passing game is almost non-existent, and that will produce more carries for Rodriguez.#4 Tank Bigsby, RB, AuburnTank Bigsby had a tremendous true freshman season at Auburn. The freshman running back rushed for 834 yards and five touchdowns on 138 attempts. Bigsby will get a more significant workload during his sophomore season.Tank Bigsby is the best RB returning to CFB pic.twitter.com/4FM1QbZQmi— PFF College (@PFF_College) May 27, 2021Pro Football Focus had Tank Bigsby ranked behind Javonte Williams and Khalil Herbert before he suffered an injury. Bigsby was the third-highest graded ball carrier by PFF. The sophomore running back has an excellent opportunity to break out during the 2021-2022 college football season.Kansas State RB Deuce Vaughn#5 Deuce Vaughn, RB, Kansas StateDeuce Vaughn is another freshman running back that is coming off a big year. Vaughn joins Tank Bigsby on the Sportskeeda top-five list as they enter their sophomore seasons.Like Bigsby, Deuce Vaughn will see an increase in his workload this season. Kansas State's sophomore running back rushed for 642 yards and seven touchdowns on 123 attempts during his freshman season. Vaughn also contributed to Kansas State's passing game with 434 receiving yards and two touchdowns.