Barcelona is a mediocre club after Messi left, there's no chance anymore for Barcelona to win either Champions League or Europa League, the best they can get is domestic league or cheese burger league. Barcelona need to sell their club to rich owner first, then they can rebuilt their club and able to compete with the top clubs.
Barcelona need to be happy if they didn't get eliminated in the quarter final match.
We can't judge Barcelona as a mediocre club when they lost Messi because after all Barcelona is a club that has a lot of achievements and even now they are still able to compete in La Liga and the European League, the problems that are happening at Barcelona at the moment can't seem to be linked to Messi because It is indeed the financial factor that caused Barcelona to lose Messi, not the other way around, if Barcelona were not experiencing bad financial problems like now then I am quite sure that Messi would still be with Barcelona and maybe he would even retire at Camp Nou.
In the last 10 season with Messi Barcelona can able to performing well at Champion League and they also can be recognized as strong team in this competition because Barcelona was never absense to qualified to round of 16 even on 2015 Barcelona can able to gets Champion league trophy after beat Juventus with in the final match and since 2015 until 2020 Barcelona can able to advances to quarterfinal several times and reach to the semifinal match once time so their achievement were very impressive but since Messi leave this team Barcelona has performance in Champion league gradually decline they even only able to finish at 3rd places on group stages two times in a row
So admitting or not Barcelona without Messi is nothing in this competition and i have no wonder if some people considers Barcelona as mediocre team however this season Barcelona achievement is quite better compared to last season because they can able to finish at first place of group standings and advances to the round of 16 and just like i said before draw result from Napoli in the first leg will be favourable for Barcelona because for second leg they will playing at Camp Nou and for Barcelona win with narrow score 1-0 or 2-1 will be enough to make them to advances to the quarterfinal and i am sure Barcelona can able to do that