Pep thinks that the players he signed to replace these players he let go can perform to their standard or above their standards, but they couldn't, and the team is becoming unbalance if one or two players get injured especially Rodri. I think things will become better since their main man KDB is back from injury and will soon start playing with the rest of his team mates.
It takes time to fully adapt to a new club and i am sure Pep knows that and didn’t expect too much from them this season. They are all quality players and with time they will transform into something else and will we see their true potential. Most players that left also joined and improved gradually until they become man enough, the team is missing them but with time they will learn to adapt without them. KDB is an important player for the team, Halland as well is an important player and without them they don’t seem too dominant as they used to be.