The hard part seems to be acurately looking at where degrees are from. I just opened my SBTS catalog and noticed in the school of theology, about 90% were from SBTS. But then when I actually started looking, I noticed that it wasn't how it first appeared. We had people from Cambridge, Princeton (2 or 3), Trinity, Mid-America, Baylor, Hebrew Union, Chicago and others, but that is just a survey.
My point is, at first glance it looked like there were a ton of SBTS alum, and there are definitely plenty of SBTS alum, but there are also plenty of other diverse schools around as well.
ETA: I just did a detailed count of the School of Theology at SBTS for 2004-2005 (the year I entered.) Of the 37 professors at that time, 12 had their final degree (PhD or DMin) from SBTS. Another 3 or so were from SWBTS, but not even half of the profs were from either SBTS or any SBC Seminary. However, when I first started looking, it looked like everybody was from here.