I can tell you why he may have yelled at Yak. Because Yak had no idea where the hell he was supposed to be on the ice. On a PP breakout, after Nugent-Hopkins and Hall had swung around to the left side, Yak also swung around to the left side, leaving every forward on the ice on the same side of the ice. Later, when Hall tried to break into the zone and throw it across the ice to the open wing, Yak came charging into the zone in front of Hall and knocked the puck back into the neutral zone. Not to mention that Yak stopped moving his feet on entries several times, stopping at the opposition blue line and making himself completely unavailable for a pass.
As far as I can tell, Hall has only been getting on Yak for not doing what he's supposed to do in the offensive zone.
And the optics are not terrible. You don't bench a guy who scores as much as Hall does for making a mistake defensively. BTW, you referenced Ovechkin earlier in this thread as a guy who breaks down defensively all the time. Guess what? He's a franchise player too.