Whenever a team is failing while having many coaches in a couple of years then the fault is definitely not their or at least partially not their.
It is the same situation as Tottenham Hotspur and several other teams, they should focus on recruiting skillful players regardless of their age and names, basically following coaches need. Other than that they will keep turning in cercles..
Well the thing is that each team management has a standard they want there club to be which is why they decided to higher a certain coach hoping that he will be able to structure the club well but the moment they noticed that he is not capable of handling it they will not think twice but to sack him and go for more quality coach that would give them the kind of quality they need, this is actually the reasons why you will see most clubs always changing there coaches all the time because they have not really gotten what they want, though sometimes I wouldn't blame such clubs because they cannot be paying there coach such amounts and he is not able to effect positively on the club.
Also I agree with you that it will be more better if most clubs will focus on recruiting quality players instead of trying to economize there money in such a way that they will use the money they were supposed to buy one players for two or three young players, though sometimes is a good strategy because there are players that was signed very cheap but now they are actually worth a lot but however for a club that needs immediate growth using that strategy may not be wise.