In his second class on Rabbi Ben Zion Uziel for Torah in Motion, Dr. Marc B. Shapiro says:
Saul Lieberman attempted to get anyone of stature to come to JTS. Lieberman posited JTS as an institution that accepts the binding nature of the Shulchan Aruch. If we fill the faculty with great Torah scholars, we can keep this as an halachic institution.
He was never able to get any gedolim to join JTS.