While I agree Chris Evans was a bad choice, lets be careful about what labels we apply to him.
Effectively Clarkson was terminated as a presenter the moment it happened. They did finish off the season with him offset albeit with one extra long episode. I'm not sure what the issue was, if they needed to go to through all the rough footage before it was released or what.
Could things have been handled better? Sure, the things that happened should not have been made public.
I still stand by what I said, there was no way the BBC could come out of this looking good. Even if it had been handled differently, they would still have pissed off a lot of people simply by firing Clarkson.
Personally, I think it would have been better to let the current version of TG die and leave it to a new team to reinvent it. It was a mistake to try and cast a new Clarkson, Hammond and May to replace the originals...