I believe that very good coaches are coaches who perform above what is expected. As for Norwich, they performed about as expected - maybe a little better considering the money invested and that they were true to their style of play.
When it comes to Everton, and we look at their performance relative to what they have invested, it is clear that Everton are underperforming. It also doesn't provide much entertainment value either (for those who care).
Then you'll probably counter with how inferior our players are compared to our competition, despite how much we've invested in them (which also points to a problem), but look at Brighton yesterday. E.g. they played with Evan Fergusen as striker, while we played with Dominic Calvert-Lewin. We played with Coady and Tarkowski, while Brighton played with Dunk and Colwill. Many of Brighton's players are relatively unknown, while others have developed over time to become very solid players.
And if you watch Brighton play football, and have some knowledge of De Zerbi, then you can see quite clearly that they play De Zerbi ball, and not Potter ball anymore. Now, of course, Potter and De Zerbi are not completely different - it is not Big Sam verus Guerdiola, but they have some clear differences. The point is, De Zerbi doesn't have the world's best players at his disposal, but despite that, in a remarkably short time, De Zerbi has got the guys playing football the way the manager wants, and with relative success.
We are a universe away from achieving something similar with Lampard. And it's quite sad to see little Brighton have De Zerbi as their manager, playing fantastic football, while Everton, well what can we say, a manager who is clearly in deep water, and who wouldn't get the job if it wasn't for the name and acquaintance.