True but even experienced players can take a season to fit in. Guess the issue for you is the pressure of having to win every game means taking time to fit in isn't allowed.
I don't think PSG is under any big pressure right now. Would have been different if City game was a loss. PSG is taking the time with Donnarumma, Wijnaldum, Ramos (not really because he might never play for PSG at this rythm). It is just that even occasionally, i don't feel anything when i see Wijnaldum play. Like, i don't know. Paredes is a very slow turtle and can't defend for shit but at least he is good at long passes. I don't see any strength on Wijnaldum. He impressed with Duth national team but he was playing higher on the pitch and won't be doing so with PSG due to the superior talent in frontline. Herrera and Gueye have been way beter than him this season.