I don't think Cassidy publicly criticized players as much as seems to have become generally believed. In his first years in charge here it almost never happened, and I think it was only in the last season, and maybe a little before, that it started to become any sort of issue. Cassidy jumped the shark when he called out Swayman in a loss that was anything but his fault, and there's no doubt that around that time he lost some perspective and I think was letting the pressure get to him, but otherwise it just doesn't strike me that he was especially hard on his players.
Nonetheless he says he's learnt some lessons from at the end of his time in Boston, so we'll see if he behaves differently in Vegas.