Succinct PM :
Up against it against a better organised and balanced side.
Arsene, play your best balanced and strongest 11 not just put your 11 best individual (or most favourite) players out there.
Play a proper HM to protect the back 4 not an attackingy type CM in this position…..and not 2 of them to make up for this as it wastes a valuable player elsewhere in the line up.
Get some width in the team and / or instruct certain players to give us that width at the right times. Tell them when this is most important.
Get more support to the striker so he is not isolated with 2 CD’s on him.
Go win game.