Overall, I would have to say Joe Montana in Football would take the cake, in the NBA, probably Kareem.
Was Joe Montana still in his prime when he was traded? Even though hockey is not as popular in America as football what about Wayne Gretzky? I don't follow hockey but I think he was still in his prime when he was traded to the Kings.
wayne gretzky for sure,probably any sport EVER
he was in shock, couldn't keep it together for press conference, there were protests
guy was more popular than any citizen of canada, he wasn't even traded to montreal but a us hockey team!