He changed the formation at half time, and then in the post-game presser he said that starting like that was a mistake. So to me that indicates that he did see that certain things weren't working.
Playing Lewin on the right isn't working, but Koeman perseveres with it, even after Lewin has shown what he can do when he's moved into the middle. Rooney and Klassen together isn't working, both players looking to work the same space, Rooney drops deeper Saturday, starts running the game. Against Man City it will probably be Lewin on the right, and Rooney and Klassen playing in the the same system again.