Liverpool's performance have dropped drastically, Sadio Mane was a key figure in the team and always came through for the team in very difficult game which they are currently lacking a player like that in the team. The absence of other first team players in the team also have an impact on the teams performance but I cannot ignore the fact that it would have been much better if they still had Mane in the team.
Liverpool players are not performing well. Nunez was brought in as a replacement for Sadio Mane, but he has yet to prove his worth. Nunez needs some time to adapt to the Liverpool team, I don't think Liverpool's performance will improve if Nunez doesn't play well. Nunez and Salah will need to perform well if Liverpool is to improve. If this duo doesn't play well, it doesn't look like Liverpool will be able to challenge for the title this season.
Sadio mane is truly a legend not only for Liverpool but also at the premier League, such player effect will always show even if he was playing at Manchester city,real Madrid or even Paris Saint Germain, but I don't think Nunes should take all the blame, Luis Diaz was the one who replaced sadio Mane at the left wing position, his performance last season is what gives Jürgen klopp the assurance to sell Mane,he believes Diaz will cover him and Darwin nunes will provide the goals at the nine position,but right now Diaz is underperforming and the team is suffering.