Some context is needed in my opinion.
People seem to forget that even now, even while they are declining due to age or complacency or whatever reason, our senior players are world class players.
They are past their prime and all, but to think that we could just pick any random new talented guy and put him in their place would make us more competitive is deluded.
- We can't just replace Pique with any CB. While he brainfarts some times (as he always has), he is still one of the best.
- We can't replace Alba, with most of the available LBs in the market. The man is a generational talent.
- We can't just replace Busquets. He has been a generational talent and a very special player (system dependent, yes).
- We can't just replace Suarez. He is one of the best strikers in the world. We would need to buy a world class striker in his prime to do that. Who is that man?
- Messi is irreplaceable from whatever perspective you look at it. No point in commenting here.
- Rakitic, when in his prime, had to replace Xavi of all people. He was many steps down, but still did a great job. Very much replaceable though.
- We were never able to replace Neymar, because you guessed it, he is a generational talent.
Replacing all these players would not make us more competitive. It would make as more average, except if we bust the bank and buy the "creme de la creme" for each respective position. Because that is what our guys have been.
The younger players that seem to be of that calibre in our squad right now are FDJ and Arthur, to a lesser extent. Mats is also a world class GK. But that's about it.
Semedo is a good player, but not a generational talent.
Same goes Griezmann, Dembele, Alena, Firpo.
The rest are below average in my opinion or too young to assess.
Bottom line is:
Valverde has damaged us in an irreversible way, because he wasted the final years of our best players without lifting the CL, while the circumstances were really in our favour.
But, we should prepare for an era (which has actually started) that Barca are not as dominant as they have been. Team cycles must end at one point, and we have been blessed to witness this team at a very high level for many years.