Yes, that's how fatigue works, I don't even Brent is alluding to it being purely physical, it onsets at after you reach the breaking point. I remember there being an article not long ago about how much weight Holtby loses in a single game, I think they talked about him getting IV drips during intermissions. To me this course of logic makes sense for last season too in the PlOffs. Every year we ride Holtby into the ground and then wonder why he stinks in the PlOffs. Brent is spot on, if you're a goalie it's a lot harder to compensate for fatigue and poor play.
This is a quality of HF Boards I've always found funny and liked though, in the same way I like bad 80's action movies. We get to have the insight of a guy who played goalie in the NHL and spends time around the team, and posters are super quick to go "I don't know, from my couch I'm pretty sure this guy is wrong." I'm not saying analysts and players are the be-all-end-all, I just think it's funny how their opinions are discarded as quickly as any other poster. Brent Johnson played goalie in the NHL for 15 years, he has covered the Capitals for 3 years, and on HFBoards his take has as much weight as Gordon from Moosejaw who is serving a lifetime ban from his local beer league for trying to stab the ref in the face with his skate.
Holtby's prior 3 seasons:
73 GP
66 GP
63 GP
I would have to imagine he is close if not #1 in games played in the last 3 years for goalies.