I feel like the culture change of going with Mount Reece Tammy was the best thing he did but in his personnel, game-to-game tactical decisions, he was out of his depth very often. I disagree about the quality statement. We had quality - much more than any of the competitors for top 4 but Lampard's decisions meant Jorginho couldn't get in the team (now he was in Ballon D'Or discussion), Rudiger couldn't get in the team (now he's top 3 CB in the league), Tomori was promoted and frozen out without an apparent reason (doing well in Italy).
This scintillating football we played under Lampard is also overstated imo. It was maybe twice or thrice over 90 mins in the first season (vs Tottenham away, Ajax away) We played much better football under Sarri (granted Eden was there) and a serious manager would have comfortably finished top 4 with that squad in 19-20.