Agree. Rather, I would evaluate his performance against the strongest opponents we faced during the season. Among the top teams, the only one we have consistently defeated is Sevilla and for the rest, we have rarely looked the better side despite a defeat
It's one thing to fail to get a result despite impressing on the pitch, another to primarily get results against weaker sides
I agree, part of why I want Koeman out is the poor performance against stronger opponents (often with Koeman looking outsmarted or his decisions looking poor)
I think Koeman often has looked bad against weaker opponents too, though.
The manager is responsible for the whole team, but we should keep in mind he doesn't influence the results extremely much. If Messi was in GOAT-form in some of these big games, Koeman could've behaved exactly like he did, and have flawless results in big games... Against Elche and the likes, no one needed to be in great form to score a goal or two. My view is that Barcelona often won despite Koeman, not because of him.