<p>There are six basic factors that drive your chances for admission:
Grades
Test Scores
Essays
Recs
ECs
Hooks</p>
<p>The letter from the professor is a rec not a hook. Having run a marathon is a nice EC but not a hook. Remember, a hook is something that BENEFITS THE SCHOOL in some way. The letter and/or the marathon may well impress the adcoms and help you get admitted, but that doesn't make them hooks.</p>
<p>People get hung up on looking for hook. Must have a hook. Gotta find a hook. Look at the list above - it's only one factor, and it's also the factor you have the LEAST control over. You have no control over whether you were born a Kennedy or a Bush or a URM or whether your dad is Bill Gates. Grades, scores, essays, ECs - put your efforts on those.</p>
<p>And BTW, it is perfectly possible to get admitted to top schools with absolutely NO hooks. A large majority of the the kids at HYPSM have no hooks whatsoever. But every one of them put together a very strong package of the the other five factors.</p>