The Gunners are back in Premier League action as they take on the champions from two seasons ago.
Mikel Arteta's team are on a ten-match unbeaten run, after they lost the first three matches of the season.
"I wasn't pleased with their start to the season. You expect your favourite team to play to a certain level and they weren't, and it was disappointing. I was disappointed by the first three games of the season," he told Metro.co.uk.
"However, they look like a real team now, their confidence is up there with the best. They've found their way and how they want to play. I'll always have trust in Mikel, I've known him for a long time. From a club point of view, I know they want to invest in young players, but for the future they'll need some of the best.
"I won't accept the club to be average. When you see the facilities, the location in London, globally you know how big the club is. Any criticism I have is like how I treat my son. I wouldn't accept less at school from him when I know he can do better.
"The atmosphere and mood in the squad is totally different to what it was at the start of the season. It's clear that confidence is key, but you need a strong spine of experienced players for that.
"You can't rely on kids. You can't do that, they are 19, 20 years old, and people put so much pressure on them, along with critics on social media.
"All this pressure can have a bad impact on their mental health. I'm pleased things are changing and have changed though as I've been through it.
"When I've had bad games, I wanted to hide and stay in bed, and I was older. So, imagine how kids are coping with it. I'm not sure I could have dealt with it so well."