You should have doubts, because you can't actually "coach" players up. That is a common misconception by non-sports guys/gals. They heard an old interview with Spurrier talking about "coaching 'em up", and they ran with it. There are cornerbacks and there are non-corners. Period. Can't fake playing out on an island. We need better players, and we have several coming. Corners and safeties... On offense you can play with wide splits and snap it quick and other gimmicks. On defense, you just line up and physically dominate. If you can. No tricks.
And if we are firing folks, fire them all. The entire defensive coaching staff. They play as a unit. Fire them as one.