Considering past statistics or current performance, Arsenal will definitely be ahead in this match. The statistics of the last five matches between Chelsea and Arsenal are completely in favor of Arsenal as Arsenal have won four of the last five matches and Chelsea have won one.
You are talking about latest matches and only last five matches between Arsenal and Chelsea. It's not full statistics of their head-to-head matches and is not enough to reflect voice of their historic fighting.
Chelsea did not have last two seasons good enough but Arsenal have been improving a lot recent seasons. It makes sense to see their last five matches have results skew on Arsenal.
If we look at the current performance, Arsenal are in great form. Arsenal beat Manchester City and started the season brilliantly, they are second in the points table although they are capable of moving to the top of the points table in the next match. Chelsea is not the best performing team in the Premier League right now, they are performing poorly in most of the Premier League matches. Arsenal will definitely win this match as Personal is currently performing well while Chelsea is performing badly.
I think their recent forms will be key as Arsenal are very confident now after beating Manchester City. Beating a biggest competitor for Premier League surely can help Arsenal players feel like they can become a new champion of Premier League.
So beating Chelsea will be very possible for them and it will take Chelsea a long time to make London derby falls to their side again. I hope Arsenal will win against Chelsea to continue their good form and to make Premier League more exciting when Manchester City will have to chase other clubs like Arsenal again.