This is definitely revisionism or misremembering. The year before Evero was hired, the Panthers had a middle of the pack defense. Then after 2 years under him they fell to the single worst defense of all time, statistically.
This year they climbed back up to middle of the pack, where we were before Evero arrived.
As far as seeing what he can do if he had XYZ players, please recall that drafting guys like DJ Johnson was his call. He pushed for these shitters and was seen fist pumping in the draft room when we gave away picks to trade up for that dude.
He's getting HC requests based mostly on his lingering reputation from the Broncos (who now have a much better defense without him btw)