Personnel isn't arsenal's problem. Give those same players to Mourinho, Conte, Pochettino, and they'd turn arsenal into one of the best defensive teams in the land
It's a structural problem, lack of cohesion and communication between the units. Stoke's goal was on Xhaka and Ramsey(or whoever the two guys who choose to put double pressure on the ball in midfield leaving jese open in the middle of the park were)
I think personnel is part of the problem, too many times I've seen fans and pundits alike excuse poor performances from our players to put the blame solely on Wenger's coaching or lack thereof.
Whatever defensive work Wenger is doing on the training pitch, I'm quite sure he doesn't tell Mertesacker to duck out of the way when Liverpool are having an attempt on goal during injury time to score a last minute equalizer. Nor does he tell Walcott to have two touches in fifteen minutes and pull out of challenges. He also doesn't instruct Xhaka to go diving in recklessly and get needless red cards.
Which leads to our main problem, our players usually suffer no consequence for a poor performance. When last season all went wrong, I'm fairly sure we played the same XI week to week. Maitland-Niles was great in the FA cup at Southampton, but he never once gets a look in after that, even though Xhaka was playing horribly. Giroud has in the past gone on an eleven game run without scoring. Then when Wenger does decide to drop a player, that player never gets a look in again, ever.
Give this team to any other manager and we'd finish no higher than 3rd. Mourinho isn't going to improve Chamberlain's end product. Conte and Mourinho are not going to make the likes of Gibbs and Debuchy competent back ups. Giroud's flaws won't magically disappear because he's playing for Pochettino
This is our level. Wenger's fault lies in the fact that this is his team, he bought these players, he coaches them and he selects the team. Yet he can't see the flaws in this team because he has far too much faith in them, when they have let him and us down time and time again. I think nearly every member of our squad is overrated to a level that's beyond their capabilities and therefore expectations are too high. We have no competent back up full backs (Wing backs), nor midfield back ups.
Not to mention that the first team players we do have are getting up in age or running down their contracts.. A proactive manager would go out and get Sanchez and Ozil's replacements this summer so that we aren't struggling to find replacements during a world cup summer next year, but that will never happen.