When Bonney was introduced in One Piece's Sabaody Archipelago Arc, nobody knew what made her on par with the rest of the Worst Generation. She had age-controlling powers, but how she used them made it seem like they were only helpful for weakening her enemies and making quick escapes. Her powers were relatively unimpressive compared to those of her Supernova contemporaries, who could throw giant-sized punches, manipulate metals, and rearrange matter in a fixed space. Thus, when the Big Eater was established as a central character in the Egghead Arc, fans had trouble imagining what she could do to influence the story once the fighting started.
Source：https://www.cbr.com/one-piece-bonney-power-endless-potential/
