@FCBarca May I ask you what happened to Carles Alena? I watched him in the CL game where we lost 2-1 to Barça at Guiseppe Meazza 2 seasons ago and he amazed me. I don't watch La Liga, I only watch Spanish clubs in European cup tournements. That's why I don't know about Alena's development. How the hell he bacame a mid table team player in a short time?
Well, it's a complicated answer. Pre-Rosell/Bartomeu, La Masia was about developing players for the 1st team. Rosell/Bartomeu era it was about using them as commodities which is also why many left the club (Grimaldo, Deulofeu, Munir, Adama, Cucurella, etc)
From there, the lack of integration into the senior team by a variety of coaches - none of whom really played the Barca style simply made it difficult for young cantera players. Ultimately, Valverde simply never played him whether that was entirely down to him or mostly down to the board (More latter IMO) is not 100% clear & that's when he went out on loan to Betis. Koeman did the same with him as he barely played him and was eventually loaned out to Getafe before making it a permanent move
Mismanagement of youth development is multi-faceted. You can have a strong structure for your academy but a coach who is uninterested in the profile or a board that sees you only as a commodity means integration suffers. Now, under Laporta & Xavi that will be more seamless and players will be developed with an eye on integration into the senior team
As for Carles, I always really liked him - kid is blaugrana through & through. I think that is a disappointment to see how poorly he was mismanaged but he is not the only one who suffered from that