Maybe
You're wrong, no?
Bellerin didn't play after the injury, Kos is living on hist past glory and I've barely seen any praise on this forum for Sokratis. Torreira is a great player but his season was ruined once we switched to 3 at the back.We (many on this forum) have been praising Leno, Sokratis, Koscielny, Bellerin and Torreira yet our defence has been as leaky as ever. If our defenders are as good as we say they are, our defence wouldn't be so weak.
The state of defence is shocking atm, and even if get some new CB in, we will still struggle to make any sort of stability there with Xhaka being on the pitch.
It's more a personnel issue than Emery.