In a baseball league the only way for one team to do better is for other teams to do worse. This means that as a baseball manager trying to buy players (in what's pretty much an auction), knowing who the best players are is actually quite unimportant, because top players generally command top prices. What you look for are the players who are undervalued by the other teams, so that you can get them cheaper than they're worth.

This really isn't the case for books, because they're generally sold at a fixed price and if there's high demand they'll just print more of them. So it's a lot more reasonable to just look for the best books and read them.