People normally get a job according to their abilities. If there were more athletes and workers than intellectuals, like in the book, people would get jobs that would require hard working and athletic types. The problem with that, is that more people work hard than actually use their brain to get something done in the first place. If people are more intellectual than athlete and worker, then there would be less entertainment and more carefully planned things.
The answer to this question, is that intellectuals and workers equal each other out. People need to put thought into the games