Why did Spagnuolo stink as Saints' DC? (merged)

When CSP returned from suspension, he fired Spags if you recall. Obviously, he and Spags did not agree on how the defense was being run or what was needed.
What might have been needed was a fresh perspective. When Spagnoulo has gotten the chance to do it his way it's worked out well everywhere else. Probably Payton's cronies also gave the bureaucratic resistance and got in Payton's ear to influence him to end it too. They probably all felt threatened.

And those guys only ever underperformed and Payton ultimately had to can them all, too late.

GIven all the outcomes observable in the fullness of time, Payton made the wrong choice, but there is more too it. Spagnoulo working for Payton may not have been a fit anyway just because of who Payton is. Rob Ryan did a good job in 2013. Then Payton comes in and orders Ryan to change it all up, take Jairus Byrd, draft some people he didn't want in an effort to try to copy cat Seattle scheme. That was a disaster and probably would have driven Spagnoulo out anyway.