The 15 Biggest "What If" Careers in NFL History

The NFL is a league of split-second decisions, unpredictable injuries, and endless possibilities. Some players were on track to be all-time greats before fate had other plans. Whether it was an injury, bad luck, or just being stuck on the wrong team, these are the players who make us wonder: What could have been?

Here are the 15 biggest “what if” careers in NFL history, ranked from intriguing to absolutely heartbreaking.

15. Bo Jackson – What if he never got hurt?

Bo wasn’t just a running back—he was a myth come to life. His speed and power made him a generational athlete, and he was just getting started before a hip injury ended his NFL career after just four seasons. If Bo had stayed healthy, he might have redefined what was possible for an NFL running back.

14. Daunte Culpepper – What if he never tore his ACL?

In 2004, Culpepper looked unstoppable, throwing for nearly 5,000 yards and 39 touchdowns. Then came the brutal knee injury in 2005, and he was never the same. Imagine if he had stayed healthy—would he have been Minnesota’s franchise QB for a decade?

13. Gale Sayers – What if modern medicine existed in the 1960s?

Sayers was a human highlight reel, slicing through defenses with ease. But knee injuries robbed him of what could have been an all-time career. If he had access to today’s sports medicine, we might be talking about him as the greatest running back ever.

12. Derrick Thomas – What if his life hadn’t been cut short?

Thomas was already one of the best pass rushers in NFL history when a tragic car accident took his life at just 33 years old. He had 126.5 sacks in just 11 seasons—imagine how much more he could have accomplished.

11. Robert Griffin III – What if Washington protected him?

RG3 took the NFL by storm in 2012, winning Offensive Rookie of the Year and leading Washington to the playoffs. Then, in true Washington fashion, they let him play through a knee injury, and his career was never the same. If he had been managed properly, could he have been the next great dual-threat QB?

10. Sterling Sharpe – What if he played a full career?

Sharpe was on a Hall of Fame trajectory before a neck injury forced him to retire after just seven seasons. He put up monster numbers, even leading the league in receptions, yards, and touchdowns in his final season. If he had played another 5-7 years, his name would be up there with Jerry Rice and Randy Moss.

9. Carson Palmer – What if he never tore his ACL in 2005?

Palmer and the Bengals were rolling in 2005, and then a cheap shot in the playoffs tore his ACL. Cincinnati never quite recovered, and it took Palmer years to regain his form. If that injury doesn’t happen, do the Bengals make a Super Bowl run?

8. Tony Boselli – What if injuries didn’t ruin him?

Boselli was as dominant as any offensive lineman ever. If his body hadn’t betrayed him, he might have been the best left tackle in NFL history. He made the Hall of Fame anyway, but we never got to see him play a full career.

7. Terrell Davis – What if his knees held up?

For a brief stretch, Davis was the best running back in football, rushing for 2,000 yards and leading Denver to back-to-back Super Bowls. Then, injuries cut his career way too short. He still made the Hall of Fame, but we’ll always wonder how much more he could have done.

6. Peyton Manning – What if his neck injury ended his career?

Manning’s career nearly didn’t have a second act. If he hadn’t recovered from his neck surgery in 2012, we wouldn’t have seen him break records in Denver or win another Super Bowl. Imagine a world where Manning retired after 2011—it’s terrifying.

5. Patrick Willis – What if he played longer?

Willis was one of the best linebackers ever, but he walked away from the game after just eight seasons. He was still in his prime, but injuries and the wear and tear of football pushed him to retire early. If he played 12+ seasons, he might be the greatest linebacker of all time.

4. Calvin Johnson – What if he played for a contender?

Megatron was unstoppable, but he spent his entire career stuck in Detroit, carrying an average-at-best team. Then, at just 30 years old, he retired early, citing the physical toll of the game. If he had played for a winning team, how much more could he have done?

3. Barry Sanders – What if he didn’t retire early?

Sanders ran for over 15,000 yards and walked away at age 30. He could have easily shattered the all-time rushing record, but the losing culture in Detroit pushed him into early retirement. The ultimate “what if” for running backs.

2. Andrew Luck – What if the Colts had protected him?

Luck was supposed to be the next great NFL quarterback, but constant injuries from playing behind a terrible offensive line forced him into retirement at just 29. If Indianapolis had built a real offensive line earlier in his career, would we be talking about him as a future Hall of Famer?

1. Drew Brees – What if Miami signed him instead of Daunte Culpepper?

Brees was coming off a shoulder injury in 2006, and the Dolphins passed on him in favor of Daunte Culpepper. The result? Brees went to New Orleans, became a legend, and won a Super Bowl. If Miami had signed him, do the Dolphins become a dynasty? Does Tom Brady’s reign in the AFC East end earlier? The ultimate “what if” in NFL history.