Another Stephen Hsu blog post
http://infoproc.blogspot.com/2014/09/harvard-admissions-and-meritocracy.html
supports Steve Pinker's contention
http://www.newrepublic.com/article/...should-judge-students-standardized-tests
that "At the admissions end, it’s common knowledge that Harvard selects at most 10 percent (some say 5 percent) of its students on the basis of academic merit."

Other recent blogs on this
Stephen Hsu (earlier)
http://infoproc.blogspot.com/2014/09/what-is-best-for-harvard.html
Scott Aaronson
http://www.scottaaronson.com/blog/?p=2003

There's a lot of great points in these blogs and the comments.