2. Inability to bounce back
Since Silva took charge in 2018, the Toffees have conceded first 28 times and have never managed to win a game after conceding first. After falling behind, Everton have managed only 5 points i.e. 5 draws, which is the worst of any team in this period.
All of this just shows that Everton did not have the mental strength to make comebacks; if they went behind, then that was pretty much it.
Compare that with top teams like Liverpool and Manchester City, who you cannot count out of the game even if they go two goals behind. Any team that is aiming to challenge for the top places and Champions League qualification cannot do so if they don't have the mental strength and spirit to come from behind and win matches.
This is not at all what you'd expect from a team which, over the years, has been known for its fighting spirit and 'never give up' attitude. The 1995 FA Cup winning side was given the nickname 'The Dogs of War' due to their spirit, but the Everton side under Silva were nowhere near deserving of that title.