This idea has intuitive appeal and is probably consistent with your business experience. In a nutshell, when economic conditions deteriorate, the ability of many borrowers to service their debt erodes in turn, along with their cash flow. More generally, we know that a recession is a period in which economic activity declines.
Speaking broadly, a recession begins when GDP starts declining, and it ends when GDP stops declining. The end of a recession is usually termed the low point or "trough." This lagging pattern can be seen clearly for commercial banks but is not as evident for credit unions because of differing reporting schedules.