I hear you Jerry, but I think you oversimplify. Not everybody who enters can win \"if they run their race\". Curlin, Big Brown and Commentator are faster than the others, by a gap. For example, Student Council needs to do more than \"run his race\" to win. He needs the other faster horses not to run.
Even if I made Commentator 10 to 15% to \"run his race\", I would enter him. The negative 5, with a trip, is very very likely to win.