The market is so inflated/distorted, it really comes down to 1) can you get the players you need? 2) Can you afford them? But in terms of
value, there is little out there right now apart from the odd loan, free transfer, and hoping some academy talent comes good. Arsenal seem to be stuck in a part of the market where the players they are going for are expensive but not necessarily a lot better than cheaper players...that's partly on them but they don't control the market, and the market is not favorable to them in terms of cost.
Johnathan Wilson has a
pretty stark - but accurate - rant in the Guardian about the stratification of football. I know I go on about this all the time, but the reality is that money determines where clubs finish. Most have zero hope of wining the league and only a couple are likely to push for a title every season.
The reality is that the 'petro-era' has changed everything. Arsenal and Spurs might be part of the 'big six' but they're out of contention for titles indefinitely. Liverpool remain dark horses under Klopp but must always punch above their weight to stay in contention. And when Klopp leaves? Man Utd are surviving on their unequalled revenue streams, but even they can't turn the taps on the way Man City and Chelsea can. And if this trend continues they too could be left behind. And, as Wilson points out, it makes criticizing managers a bit of a red herring in general, unless they're obviously duffing it.
No manager can make Arsenal competitive with Man City given the disparities in wealth, talent, and depth of squad.
Sure, on any given day or any given season an anomaly can occur, but the exception just proves the rule.