I don't know what you are talking about. On the one hand you are saying it's not about individual quality, on the other hand you are blaming one person for two individual actionsWho cares how good they are relative to their club team mates or who they play for. That is not how football works
Upamecano has been worse than poor. Almost gave away 3 pens to England.
A defence has to play as a unit. The CB's need to complement each other. The manager's tactics decide how they play (what they do) and they depend on cover from players higher up the field (where tchoumeini was not good defending and rabiot was not holding position).
It was better that Upamecano missed this game and that Kounde played a more defensive minded role in midfield this match.
If L Hernandez wasn't injured they could've played with 3 players who start together in Munch who have among the strongest defenses in the world.
But they wouldn't do that, because Varane is a better leader and generally a player than Pavard and Upamecano. There's more dimensions.
This is national team football, defense will never be amazing alone unless your whole team plays defense like Morocco. France does not stand out in any of the great teams as being weak.
England is the only team that had them shaking, as they should've. Just as Argentina did last time. Just like the best teams should do to each other, or are you saying that the English offense is so trash they should've not even reached France goal while being down 1?