How the fuck did they get David Dastmalchian to play Mr. 3… this dudes been in multiple major movies.
I'd imagine One Piece is well-loved in many creative fields. Film RED was great at introducing the series to more celebrities in film/music, as the film was very successful on an international level.
Sports and Hollywood often share popular topics, and anime has been huge in sports the last few years.
Also, Mr. 3 actually does a lot in Alabasta, and if they expand his role they could easily cut out some other characters to justify throwing a ton of money at him (like Mr. 7 and Ms. Father's Day in the clock tower).