I'm not going to read this thread since last night because I'm sure it's full of very insightful, constructive criticisms...
The Arsenal game and the first half last night are how Koeman wants us to play. High intensity, with energy to press the midfield which allows us to defend high up the pitch. Unfortunately, we don't have enough players to allow us to do this when injuries come along, as was shown by the shift in play in the 2nd half when barry came on. Lukaku and Barkley became isolated because some of the energy from midfield had gone and we had to sit deeper.
There are positive signs as far as I'm concerned. Once we get more players in who have the attributes needed for the game Koeman wants us to play, we will see more performances like we did against Arsenal and the first half last night, which will see us win more points.