I had a revelation while reading through the book on W. A. Criswell - Joel Gregory's Too Great a Temptation - since the author was so enamored with the size of Southern Babtist congregations.
Many people are earning degrees (MA, MDiv) in ministry, children's ministry, youth ministry, and urban ministry without considering a mainline denomination as their host. At the same time, mainline seminaries - including all the Lutheran ones - are collapsing for various reasons.
The big ol' seminaries cannot bear to part with their physical plant, built up and overbuilt with so many odd fantasies in their minds.
Congregations are better off with pastors who are believers, rather than with synod loyalists who are drowning in debt and false doctrine the moment they graduate. I often think of the UCC, since my parents took us to a Congregational parish in Moline. The Congregationalists became the United Church of Christ through a series of mergers and now barely exist.