What priest shortage?

The May issue of the Knights of Columbus' magazine, Columbia, has a thought-provoking article by the Rev. Michael P. Orsi. In "Heroes: Then and Again," Fr. Orsi writes,

Our most common mistake is forgetting that God will always provide for his Church. . . . [T]he decline in vocations actually began before Vatican II, and [Sullins' book] points out that the decline in the priest-to-parishioner ratio after Vatican II has been largely offset by the decline in Catholics attending Mass and requesting the sacraments.

This seems so obvious that I wonder why it didn't occur to me earlier.