re: When did the SEC start this decline? Is it really Saban’s fault?

There really is no secret to what caused the decline and why it happened. Ultimately government employees lacking the basic skills for hiring employees. The formula for hiring good employees is really no secret:

1) Hiring a coach with the same goals/values as the AD/administration.
2)Extending trust instead of micromanaging.
3)Clear expectations.
4)Accountability - Response to mistakes
5)Competency

And ultimately 6) delivering results. When you violate 4 out of 5 in your hire, you should not be surprised when the coach doesn't deliver results.