If Barcelona loses this player, then there may be a negative change in their team's performance, on the other hand, if he can adapt himself well with Chelsea, then he can change Chelsea's performance. That is, according to various media reports, Chelsea has spent or is going to spend 40 million euros for this player's contract. When a player can play a good role for a club, then only that club management is ready to spend such a large amount of money for that player.
Although we have not received any such news from Chelsea or this player so far, based on which we can definitely say that the contract between Chelsea and this Barcelona player has already been completed. However, if this contract is between the player and the team, then I think this contract will benefit both parties.