Qwiss That's a pretty big assumption. Merino has been fit for quite a while now and this is the first time we've seen that midfield. Its pretty clear Arteta sees Partey, Rice and Odegaard as his best midfield 3.
I don't think it's that big an assumption. Arteta said this, literally last week:
“There have been a lot of new units recently. Certainly, that was one. That’s one that obviously we have planned and discussed and I think they can play so well together. And they did a really good job.
“They will play again together for sure in the near future and I think they complement each other really, really well.”
There's more if you want to read it here:
https://arseblog.news/2024/12/arteta-happy-with-new-midfield-trio-doesnt-mind-attacking-imbalance/
It's not that surprising Merino's introduction has been gradual, given the injury he suffered almost immediately and then adapting to the way we play football as well as a new league.
And no, I don't think it's just one midfielder causing us all these problems. I think it's the injuries we've had, the form of our attacking players, Saka excepted, Odegaard being out, the red cards we've had and, nobody wants to hear it, but a pretty punishing away schedule this season. How many teams have had weeks like this on the schedule? We've had two of them...
Spurs - Atalanta - City
Newcastle - Inter - Chelsea
Arsenal are a big club. I get it, there shouldn't be excuses for losing games, but it's asking a lot to expect us to come out of these weeks unscathed.