I don't remember many people saying fielding percentage is "laughably worthless." To me, it is somewhat useful at the extremes (especially low extremes). If someone has played 100 games at third base with a .850 fielding percentage, I'm relatively certain they presently suck at playing third base (or official scorers have a vendetta against them). OTOH, if someone has a .950 fielding percentage at third, I'm relatively certain they aren't Ryan Braun bad there, but I need a lot more information to determine anything other than that. I think it's more of a point of entry stat than anything that should usually be used to make a determination about someone.