I think he may have become a little over confident. it worked in the past and usually gets' away with it. I think he started to look like he'll deal with things slowly and with ease and it's not really worked.
Gabriel needs more praise. And to think Arteta wasn't playing him at the start of the season.
I remember that ball! In his defence, he was trying to play Martinelli in on goal with a narrower pass, rather than the safer pass wide. Worth the risk there, but he got it a bit wrong.
We are not very good at this game management stuff yet. It affects our decision making about where and when to take risks and often ends up making us slow and predictable. And then vulnerable to errors.