The rivalry between this two teams is what I feel made this match very tough and also Arsenal needs to win the match in order to have a chance to retain their second position on the league standings. The point gap is really what Arsenal should really look into in order to not feel relaxed playing in this match but in the end, the game ended draw. The remaining two match is indeed important for them to retain their second place because if they fumble, they may not finish the league as runner up.
Don't be surprised if they end up 3rd or 4th 
If Arsenal end up 3rd or 4th, it's inconsequential because what is is only important to them is appearing at the champions league next season which is already settle no matter what the outcome of their remain match is. Arsenal have been consistent in qualifying for the champions league and this year is just like other years which they always perform as usual.
If Arsenal can put themselves together and start getting serious, they have all it takes to win the Premier League and even the champions league.
Regardless of whatever position Arsenal finishes in the final standings later, they have definitely gotten a ticket to the Champion League next season and that's enough.
Regarding the improvements that Arsenal must make to be able to win trophies, I am very pessimistic because they have done it in the last few seasons but continue to fail, even this season their overall performance has not improved compared to last season.