I believe his presence in Chelsea squad will boost their weak defence and with age on his side and a long term contract agreement, I believe Tuchel will norture and mould this guy to a world class defender he is very young with a bright future personally I think his sign-on looks too expensive to me, just like when Man Utd signed Maguire from the same club, I hope he delivers for the club
https://www.bbc.com/sport/football/62462069The signing of Fafana is a good deal for the blues because the young defender still has a lot of strength in him to help in the defense line of Chelsea who are currently having issues in their defensive line. Fofana's signing fee was much but I believe this is now a norm for players coming to EPL, maybe because the deal is a long-term deal but for a player like him that deal is outrageous but considering the case of Harry Maguire who also cost £80 million to Manchester United but couldn't give a good result, I hope the situation of Fofana isn't going to be so because a lot is expected from him. Tuchel will make him do better but we should not expect him to do above his ability for now because he's still very young and may take some time to adapt to the quality we want to see in him.