Skinner reminds me of JSG from way back. The guy is just big. He doesn't save pucks, per se, but rather is in position to block them because of his big size. Neither are particularly athletic goalies, especially with Skinner. Like the first Mackinnon goal where he comes off the boards towards the middle, it was basically a routine glove save and even Skinner failed at that.
People hate to fat shame and whatnot but Skinner really needs to go on a diet and come back leaner. Would at least help his agility. It was a topic of discussion on the internet comparing Skinner to the rest of the league. Hes one of the heaviest goalies relative to his peers (Vasilevsky being the outlier as we all know how extremely athletic he is, despite his height and weight). Skinner's problems are both physical and mental. Mental may take time to grow, but physically, he can fix that if he can be more self-aware and realize it will help him more immediately.