The nature of college football is filling in positions for departing players.
But some Big 12 players will be facing bigger challenges than most.
Here's a look at the players who will be the toughest to replace across the Big 12:
1. Texas QB Colt McCoy: He leaves school as the most statistically proficient quarterback in school history, although his career will forever be marked by his near misses in the Heisman Trophy balloting over the past two seasons and his injury in his final college game against Alabama. Garrett Gilbert will be facing some big shoes to replace when Texas practice starts later this month.
2. Nebraska DT Ndamukong Suh: He will go down in history as arguably the greatest Blackshirt ever, a player who stayed in school for an extra season and cashed in with a haul of individual trophies. Terrence Moore will accept the huge challenge to replace the most dominant defensive force in Big 12 history and in recent college football history.
3. Oklahoma State CB Perrish Cox: His ability as a shutdown cornerback and a punt returner helped marked the Cowboys' defensive effort last season. Cox led the Big 12 with 19 passes defensed and he didn't play in his final game in the Cotton Bowl. Overachieving 5-foot-8, 180-pound Brodrick Brown will have the unenviable task of trying to replace Cox in the Cowboys' secondary.
4. Oklahoma DT Gerald McCoy: Although he was sometimes overshadowed by Suh in the conference, McCoy was the anchor of the Sooners' defense during the past three seasons, notching six sacks and 15.5 tackles for losses last season. Heralded Jamarkus McFarland will get the first shot at replacing McCoy -- not only in his production but also in his leadership.
5. Missouri WR Danario Alexander: The Tigers will bring back starters Jerrell Jackson and Wes Kemp, along with heralded rising sophomore T.J. Moe. But it still won't lessen the contributions of Alexander, who blossomed into the nation's top receiver over the second half of the season, finishing with school-record single-season totals of 113 receptions and 1,781 receiving yards.