Is it possible this could be as simple as Deron was unhappy loosing, was trying to push his ideas, Sloan resisted, Deron got frustrated, Deron and Sloan argued, Sloan realized at the end of it that he didn't have the energy to do what needed to be done for the team so he called it a day and stepped aside? Just maybe this was Sloan's decision and it was what he said it was, he didn't have the energy the job demanded. Didn't have the fight left to take on frustrated players, management and fans. Realized that even given a few more years he wasn't going to get a title or have an elite team, so finally asked what would the point be of sticking around.
Maybe?
Or Deron told management to can Sloan's *** or else, and then KOC gave Sloan the news that his time was up.