Robin Hanson saw Moneyball:

Along the way, the movie vividly depicts profit-driven buying and selling of people, over which the people involved have little say. If traded, players must immediately move across the country, with little compensation. On the screen, it sure looks a lot like slavery. But I can’t find a single mention of slavery in any of the Moneyball commentary. It seems viewers don’t even notice the issue — even viewers who don’t know or care much for baseball, and doubt baseball makes the world a better place.

This supports the theory that we see “slavery” as low status by definition – so by definition anyone high status can’t be a slave.

That’s possible! It’s also possible that Major League Baseball players make a minimum salary of $414,000/yr, which would put you in the "vastly wealthy" category by almost any estimation. Also, you could stop playing baseball any time you like, which is an option unavailable to most people who are uncontroversially called slaves.

There is a usefulness to analogy, metaphor, etc, but there is also a usefulness to protecting the integrity of certain words. This is slavery. Playing shortstop for the Chicago Cubs is decidedly not slavery.