Casey would not have won. Nurse's system was better then Casey's, and Nurse outcoached Budinholzer and Kerr in the playoffs. Do we forget how bad of a coach Casey was in the playoffs? It's not even close who the better coach is.
Casey was getting outcoached by Tyron Lue of all people.
Nurse's coaching history:
Year 1 - wins with Kawhi and co
Year 2 - overachieves (note that the entire success of that season is due to opponents missing a lot of open corner threes, aka luck)
Year 3 - Tampa tank, poor D catches up
Year 4 - low expectations, team makes playoffs and loses in first round due to the same defensive issue
Year 5 - last year, refused to play a bench, same defensive issue
5 years, 2 1sts, 2 3rds and 2 5ths but one of the 5ths required one of the most inexplicable shooting lines against in NBA history.