When one important player leaves the club, the team's performance will change. We've had so much evidence so far, it doesn't just happen to one club but to most clubs in multiple leagues. Liverpool experienced a decline in form because Mane left, as well as when Ronaldo left Manchester United to join Real Madrid.

It's true the team will be looking for a suitable replacement, but sometimes adaptations don't go according to plan. New players need time to adjust to their new friends and team, after all they also have to learn different strategies and training portions from their old team.