I don't see how the coach becoming emotionally unhinged helps the team one bit. Especially as there are players like Marchand who would then follow his example and end up taking unnecessary penalties.Something emotionally would be nice, I am not a fan of whining either but at least let them know you are upset. Staring off in to space and chomping on some ice does nothing.
Cassidy does express his displeasure with calls; he just doesn't do it in an exaggerated way like some other coaches. Is there evidence that that hurts the team somehow? I'd like to see real proof before I get onboard with that idea.
If he "showed emotion" in the way some fans would prefer, that would make those fans feel better. So what? How you or any of us feel has no impact on whether the team wins or loses.