My guess is that it isn’t so much that churches are leaving, but that new congregations that once might have called themselves “Southern Baptist” are now declining to brand themselves.
At the same time, I’m very concerned (full disclosure: I’m Catholic) that Dick Land is trying to make the SBC align itself a little more with the Democratic Party, on issues like environmentalism, immigration, and Islamic relations.
(Don’t get me wrong, I’d still rather Dick Land’s politics than the aging hippie crap that I have to put up with from Northeastern Catholic priests, but then they’re in the northeast, where the Northern (now, “American” or “First”) Baptists aren’t even remotely Christian, let alone politically conservative.)