#1 Lack of cohesion between players
When you spend such a big amount and bring as many as 10 new players, it is obvious that they are going to take some time to get used to each other. Add to that the fact that most of these players are playing in a system which has 3 at the back for the first time.
This has been evident in all the 4 defeats. Most evident has been Michael Keane‘s lack of connection with his fellow defenders Ashley Williams and Phil Jagielka. His lack of understanding of the system and his partners often drags both Williams and Jagielka off their positions.
Everton can still make a comeback in the race to top-4 as it is still early in the season, but Koeman needs to first figure out how to get the best of his players and settle down with a system which works best for the kind of players he has. The only way he can get the best out of Rooney and Sigurdsson if he can inject some pace in the team in form of the impressive yet underutilized Ademola Lookman.