If Dean goes on to become a good manager (which I think he may do, there were flashes of really good stuff under him here [against Leicester and BCity, specifically] and he's obviously doing something right at Crawley for the moment) I don't think that changes the fact that, at the time, he was absolutely horrendous for 99% of his spell here, absolutely needed to be fired, and was the wrong choice to replace Ståle from the get-go.
As with all things, people grow and change and become better (or worse) at anything they may occupy their time with. I dread to think what some Wolves supporters may think a few years from now if Dean has notably improved. Will we see a faction of the support that will say again that we should never have sacked him? Perhaps.
Anyway, just rambling.