What is a bust in fantasy football?
A bust is a player drafted at a high cost who badly underperforms expectations, returning far less value than the pick used on him.
A bust is the opposite of a sleeper — a player you paid a premium pick for who flops and tanks your draft value.
A running back taken in the first round who misses time with injury, loses goal-line work, or simply plays poorly is a bust because the opportunity cost of that high pick was enormous. Busts hurt most early, where you've invested the most draft capital and have the least margin to recover.
Busts come from injuries, changed roles, regression from an unsustainable prior season, or simply paying for name value over real opportunity. Avoiding early-round busts is often more valuable than hitting on late-round sleepers.