New coach would bench our rookies and go for the wins with experienced guys, but still couldn't make it to the PO. So it looks like an easy decision to keep Casey. Also it's quite a new roster, 3 new starters, so it takes time for coach and team to adjust (LA Lakers for example. oh wait, they fired Brown, so maybe not Lakers
). There are pros and cons that I see in both keeping and getting rid of DC, but pros of keeping him are bigger.
You can give second chances many times, but fire only once. So better give all chances possible before you're sure it's time to fire.