Its not important what happened after him, but what happened before him. The fact is that the years before, Barca was competing for the title, City was competing for the title, Bayern just won the treble before he joined! Maybe these teams needed some rebuild within the team, but Im talking about the clubs. All these clubs were stable, all these clubs have been champions within some years before he joined, all these clubs were competing every year. The fact that Pep only won 1 CL in the last 10 years with Bayern and City is not a good performance tbh.
On the other hand we are not competing for the league title for 6 years now.
Pep always was in a comfy position when he joined his clubs. Hes not doing wonders. Wonders would be to make United champion again after SAF, making Chelsea champion again after 6 years, winning the CL with clubs like AC Milan after 16 years. To transform a club from mediocrity to being world class.