IMO Sloan quit because he's a seventysomething year old man who's diminishing testosterone levels left him without the fire and energy to deal with another hot headed player. Do any of you want to be doing your current job when you are seventy years old? Sure he misses it now, and might do the stupid thing and try it again, but I know for sure that I don't want to be doing my job past seventy. (if I even live that long)
I also agree that he wanted to give Corbin a chance at the job, and I'm glad he did, Corbin is doing great right now. (also My opinion)