Exactly this.
A lot of people seem to think Managers are 1 size fits all, but there not.
Mid table is Emery’s playground. He’s great at taking a solid club and getting a bit extra out of them to push the top teams over the season, and do well in cups. However his time at arsenal and PSG show that he’s not able to have that same impact at a higher level.
To be clear, I know there were other issues not of his doing at Arsenal, and I’m sure his time at PSG had similar issues. However, I think successful managers at that level are able to impose their will on the club and team to get what they want, like Arteta has done. The fact that Emery was overshadowed by the other club issues shows that he’s not at that level.
How would it impact his legacy at all?
He’s entire legacy is that he takes the richest team in the league that’s loaded with stars and is extremely successful with them. That is exactly what he did at Bayern and Barcelona.
Just because Man City cheated to be the richest team in the league doesn’t change how we perceive Pep’s performance. We already knew they were the richest team in the league and cheated to get there before Pep joined the club.