I agree with you — inconsistency is maybe Arsenal's biggest problem and one of the reasons why they haven’t won anything in the last five years.
The main reason why Arsenal have been ending the season in second position is just inconsistency, Arsenal are always having chances to win the league title, but their performance is always dropping. Mostly Arsenal will start the season well, and everyone will think they will be able to win the premier league title that season, but before the season ends, you going to see that Arsenal will start losing matches that they are not suppose to lose, I don’t really know why thats always happening to Arsenal, but with the new signs which they just made, let’s hope next season is going to be a different season for them.
Inconsistency in what way exactly? I don't quite get your statement well or may be I am misinterpreting it. Arsenal have not been good enough to keep their top performance from the beginning till the end but to me they are one of the most consistent team in the league in recent years always finishing second place and maintaining it every year is something. They consistency is not in performance like Chelsea, Manchester United and others but they fail to be champions one way or another.
I believe why lose matches they are not supposed to lose is because they didn't have a prolific striker. There are match your striker wins for you singlehandedly and that's what Arsenal lacks all these years, I just hope Gyokeres will finally help solve that problem.