Check your competitions.
Everyone applies with 3.9GPA ish and I am guessing a few 4.0GPAers will pop up. Not to mention they probably have a lot of letters of rec from distinguished physicists. Yeah I agree, it probably is over 950 on their GRE.
A lot of published research and I say most of them are from reputable alma maters. Don't get me wrong, I am sure there are equally successful applicants from less reputable undergrads, but just more will come from say Harvard, Yale, MIT, Cornell, Chicago, etc..
Also, I heard that minorities have a different applicant and is rumored to be easier, not sure if that is true though.
Then again, what do I know?