Some roles will show an immediate change. Some will take time for the changes to be apparent.
Take our not so loveable neighbours for instance. If you can score lots of goals but because you have a bang average goalkeeper and defence, you keep losing valuable points, but you can afford to go out and break transfer records to sign 2 of the best players in those positions, you will likely see almost immediate improvement in results. More is the pity.
On the the other hand, if the problem is that your players are not fit enough because you are cycling off whatever "energy drinks", asthma medication or blood doping processes you have installed, then you are just going to have to wait and let things play out until you are in a stronger position to go again, even if you go from runaway champions who dropped 2 points by march in the 1 year to the worst historical home record in the clubs existence the next.
The point is, if Brands is ever going to be successful in his role, it is not something that would ever be instantly apparent or even within 3 years, especially when trying to fix the mess he was left with. And yes, in some respects, he may have partially added to that in the 3 years he has been here, but at the very least, it was with good intentions.
What is the alternative? Say he has a plan and is going to stick to it, so insist we only sign 16 year olds and sit back and wait? We still had to improve the side for the here and now, and in the main part, we have done exactly that, with mostly younger players with a higher ceiling, while trying to shift the god awful mess we were left with when he arrived.
Yes, a few signings have been underwhelming and/or failures, but some of that is also down to bad luck (Gomes and Gbamin for instance).
It's all well and good saying he does nothing, but you don't actually know that. You assume it, because the results you demand/expect haven't arrived yet. And they may not for another 4 years or more.
The indications though are that there has been an overhaul at youth level and we are starting to see the shoots of this coming through. We have signed, with a few notable exceptions, generally a younger crop of players with an eye for further down the line.
If you are expecting instant success from a director of football, taking over this basket case of a club, who spent the previous 2 years handing out insane contracts that no other rational club would consider to bang average journeymen who each arrived with their own humungous transfer fees that we would never be able to claim back in month of sundays, a club who had already hired and fired 2 managers in the previous 2 years, also on ridiculous contracts, and were still paying each of them off as well, and at the same time, had a transfer ban on youth players to contend with, then you really need to take a look at the criteria for your expectations.