<p>It's because Yale accepts more legacies, URM's, and athletes during the first round, as does any other school with EA. Also, the first wave of applicants tends to be stronger, or at least that's the general consensus. There's a reason why Yale chooses to pick more out of the first (and smaller) pool.</p>
<p>Basically, it's more or less Darwinism. If you're fit and you'd definitely get in during regular decision, why not accept you earlier?</p>