Arsenal twice came from behind to salvage a 2-2 draw in Sunday's friendly with Hong Kong champions KitChee.
"In the second half not so much because we were not challenged. Defensively we have a lot of work to do as a unit to do much better.
"We let everybody play and some players are not yet at the level of the Premier League. It is a learning process. If you don't do it in pre-season then you never do it - you give them a chance to see what is requested at the top level.