To be fair to DeSmith, its not like that was a clear sight shot on goal that absolutely should have. 100% been a save. That shot was going far side, DeSmith had to look over the screen of O-Reilly+Hughes. He sees the shot going to his left and because he loses sight of the puck his best bet to make that save is to square up to the puck, hence why he slides over, then the puck takes a 45 degree turn the other way. In order for DeSmith to get back the other way he has to push off which requires him to have to scrunch his outer leg up and push off back the other way. The problem with that is it requires his body/right pad to move further away from the puck before he can explode back the other way. He had no real chance unless he had legs like Vaseline, or some 6’6” goalie whos legs are a longer.
Its pretty hard to blame DeSmith, he even dropped back in the net to give himself some space for reaction to a bounce off the screen. He started at the top and then slid over and slightly back in his crease