Kos, Cazorla, Özil, Alexis. An irreplaceable spine. All 4 are extremely difficult to replace currently.I think a decent part of the reason he's not appeared to be as much of a standout player so far this season is that the rest of the team has raised their game up closer to where him and Alexis normally reside, as opposed to him really dropping off all that much. He can still go up a gear, has been sloppier sometimes than you would expect, but he's been a consistent threat every game and he's always contributing to pretty much every attack in some way.
Still learning his new role as well, as is Alexis. They are almost like a new strike partnership for us at the moment and it's just going to keep getting better I think. Özil's movement is helping Alexis a lot as the CF, as he gives him space when he runs beyond, and they are combining very well regardless of who is on the end of chances. And I mean this whole discussion about Özil's form is coming at a time he is scoring at a better rate than he ever has for us, and the team is in the midst of a great run of results. I don't think there is much to be concerned about.
Overall he's still our most integral player apart from Kos I would say, in that when they are fundamental to how the team plays at its best.