Arsenal still like to transfer young talents a lot. Fabio Vieira seems to be one of that kind of players. However, Arsenal shouldn't make do with this kind of transfer in the summer too. They obviously need some star players in the team now to fight harder in the Premier League. They had a wonderful season despite starting badly and finished at the 5th place.
To allure quality players your team needs to be in the Champions League, and if you aren't in the Champions League, then you should be able to offer quality players a very fat salary in order to concvince them to move to your team, Arsenal can't offer any of the above, they are not in the CL, and they do not have the sort of budget to offer fat paychecks to players.
Thus having said that, they have to be moderate, the coach is not doing any badly with what the board is providing for him in terms of funds, what ruined their season last time out was that they missed out on CL football for next season, even after being in the driving seat for so long; well they can look forward to next season, they are making good signings in my opinion, Gabriel Jesus looks set to be joining from City and he is not coming for cheap either. The thing is, a top four finish will be good for them, as i can't see them winning or even challenging for the EPL, then they can try to win a domestic League Cup, either the FA cup or Carabao cup.