Have you seen Barca the season before Pep? They finished 3rd and won nothing. There was a disconnect between the fans and the club, which grew resentment towards Rijkaard. They sacked him, appointed someone who knew the club and the culture. This in itself had players believe in the manager and in their ability.
Do I believe this will happen with Lampard? No, because I can't back that up. I do however know Lampard's philosophy on football, and I think it will help continue on what Sarri started.
Again, the one thing we need to know is what the club expects from Lampard.