Adrian Peterson
Peterson was an iconic NFL running back and a brilliant athlete. Many sportspeople think that this is enough to forge a career in combat sports. Often it’s not because boxing and MMA require different types of conditioning. Furthermore, it’s difficult to learn the skills in a short period (via NFL.com).
In 2022, Peterson fought fellow NFL star, Le’Veon Bell in a boxing match. But he suffered a brutal knockout loss in the fifth round of their heavyweight clash. Nobody wanted to see the future Hall of Famer absorb this type of damage after a tough career in the pro football ranks.