Some would be of the opinion that arsenal have already done their best and its just that Manchester City and pep Guardiola are too resilience to that fact that Arsenal also have earned the right to win that trophy and for arsenal all they can do is actually to just keep on recruiting players and making their team strong enough for them to actually come out of the shadows of Manchester City and pep Guardiola too.
The reality is that it is like that and maybe it will continue as long as Pep Guardiola is Manchester City coach. The reason is that it is very difficult to break Manchester City's dominance, especially since sometimes they start to get serious towards the end of the season. On the other hand, Arsenal were very good at the start of the season but they often stumbled at the end of the season which resulted in them losing a lot of points.
Arsenal's losses were then put to good use by Manchester City to overtake them and we have seen this over the last two seasons. However I actually hope Arsenal can win the trophy but they don't even have the luxury to emphasize to their rivals that they are worthy.