I disagree. Imagine if we had signed some "proven" player instead of Umtiti and Nelsinho. Lets say Benatia and Bellerin. Would it have been better? Signing young quality players (what some might call "talents"), is the way to go as they age over time and new young players can be signed, always making the squad a good mix of experience and young quality.
Except Bellerin is barely more proven than Semedo.
Apples and oranges.
We needed a young CB for the future with our already established CB duo in Mascherano-Pique and we needed a young RB since any established RB out there was impossible to get since....news alert......there are very few established RBs out there in the first place. Most of them are either young, had one breakout season or simply average/mediocre.
For the midfield however you need World Class players. Barca need to have their midfield improve right away. It need to be players who can add something and increase the quality of the team right away, not a project who's 2-3 years away from reaching that stage, especially since we already have a project in Carles Alenya.
Does this mean 25+ signings? No, age doesn't matter here, but it need to be someone with those characteristics. Is Torreira that? Not yet, but he might be that soon. I would sign him, BUT only along with a WC MF.
I don't care about their ages. It need to be someone who can add quality to the team and make us a serious CL contender right away.
That's why you need players such as Coutinho or Lemar who will cost more or less the same now. Not Fabian Ruiz or Carlos Soler.