Arsenal was in a better position to challenge Manchester city to win the premier league title this season, they were in a better position to getting that done but they weren't calculative enough to know crucial games and handle them as such rather it felt like they did treated every game like the same at a point in time until they were just few Weeks to the end of the season they took every game serious knowing about their rival.
You are right. And I also observed this from Arsenal this season: when they started the season, they were not as serious as they were when the season was about to end. At the start of the season, Arsenal was playing well, but they were using the same tactics in all their matches, which are both small clubs and big clubs, and I think that’s why the result ended like this. If Arsenal were not very serious with every match from the first place, I’m very sure they are able to concur with Manchester City.
And this is what helped Manchester City; they are taking all their matches seriously regardless of their opponent's performance; they don’t underrate teams; and this is what Arsenal is also supposed to do because a team you underrate may be put in shame, and I think this is what happens: Arsenal always ends the season with mistakes that result in their failure to win the title.