I'm watching the VOD of the classic pinball tournament at Free Play Florida, and Escher Lefkoff (#1 pinball player in the world) is doing commentary.
His commentary at one point was "He hit flag 3 and -- well I could talk about the strategy but I assume everybody knows how to play Wizard."
Wizard is a pinball table from 1975 that might be the most complex electromechanical table. I played it a week and a half ago in VPX and I don't know the strategy for Wizard! I certainly don't remember what flag 3 does. Most people know nothing about Wizard at all.
This is a problem you get, I guess, when the #1 player is commentating. There's a view from the top where you just forget what it's like to not know things. But even if the strategy of Wizard were obvious to every viewer -- he should still talk about it. You can just talk about things that people already understand. That's commentary!