~~
I totally agree with you about how Arsenal buys players. Team has spent a lot of money on new players in last few years but they have not always played as well as expected. To really make team stronger Arsenal needs to be smarter about who they buy. They should choose players who fit with coach plan. Also as you said they need to make their backup players stronger. This will help them keep playing well even when their best players get hurt or are too tired. If Arsenal can do this they will be able to reach their full potential and have long term success.
I haven't checked whether Arsenal are involved in the hunt for players this winter, but if they are indeed targeting players, they should recruit what the team really needs. In fact, what they need right now is a pure striker who can be a goal machine in their squad, as for other players, maybe they can bring them in the summer transfer window after conducting a team evaluation as a whole. Regarding the second reserve player, Arsenal actually has experienced players. So what Arteta should focus on is returning to the pure striker they were targeting in the previous season, or a qualified winger, because it seems like Martinelli is difficult to rely on consistently throughout his match. Regarding the competition in the Premier League competition, I think the opportunity is still wide open for Arsenal, it's just that it won't be easy for Arsenal, especially since Liverpool is performing well. However, this competition still offers something interesting.