Players like Arda, Vidal and Vermaelen havent really worked out either. The value of 26 year olds for us is lower as well as we have to replace them sooner for huge amounts. There is a reason why Inigo is still playing for Sociedad at 26 years old. He expected to finish his career at that level most likely and is as shocked as the rest of us about Barca showing such interest in splashing massive money on him.
Players who are 25-26 wont improve and become true greats. Thats why its not common for top clubs to spend huge amounts of money on 26 year olds. Its a luxury to do so. The main problem we have is not the age of our signings but crappy signings, regardless of age and nationality.
About buying players aged 18-22:
Look at all players bought since 2003 (Laporta):
18:
Quaresma, 1/5 (ratings are my personal estimations of player's Barca career. Others may not agree with some ratings)
19:
20:
Keirrison 1/5
21:
Caceres, 1/5, 3 seasons
Neymar 4/5, 4 seasons
22:
Henrique 1/5
Chygrinskiy 1/5
Alexis 3/5, 3 seasons
Ter Stegen 5/5
Denis Suarez 2/5
Umtiti 5/5
Digne 3/5
Andre Gomes 2/5
23:
Ronaldinho, 5/5 success, stayed for 5 seasons
Etoo 5/5, 5 seasons
Jordi Alba 4/5, 6+ seasons
Paco 3/5
24:
Marquez 5/5, stayed 7 seasons
Yaya Toure 4/5, 3 seasons
Afellay 1/5
Fabregas 4/5, 3 seasons
Alex Song 1/5
Douglas 1/5
25:
Dani Alves, 5/5, 8 seasons
Aleix Vidal 3/5
26:
Deco 5/5, 4 seasons
Milito, injuries
Mascherano, 5/5, 8+ seasons
Adriano 3/5, 6 seasons
Rakitic 4/5, 4+ seasons
27:
Guily 4/5, 3 seasons
Belletti 4/5, 3 seasons
Abidal 5/5, 6 seasons
Hleb 1/5
Ibrahimovic 3/5
Maxwell 4/5, 3 seasons
Luis Suarez 5/5, 4+ seasons
Cillessen 4/5
28:
V Bronckhorst, 5/5, 4 seasons
Edmilson 4/5, 4 seasons
Sylvinho 4/5, 5 seasons
Van Bommel 4/5, 1 season
Ezquerro 1/5, 3 seasons
Gudjohnsen 3/5, 3 seasons
Keita 4/5, 4 seasons
Villa 5/5, 3 seasons
Vermaelen 1/5, injuries
Arda 2/5
29:
Zambrotta 3/5, 2 seasons
Henry 4/5, 3 seasons
30:
Rustu Recber, fail
Mathieu 3/5, 3 seasons
31:
Bravo 5/5, 2 seasons
32:
33:
34:
Thuram 4/5, 2 seasons
************************************
************************************
Age 18-22: 3 good players out of 12 attempts.
Player who turned as starters and good enough: Neymar, Umtiti and Mats
Failed or not good enough to keep them: Quaresma, Keirrison, Caceres, Denis, Gomes, Chygrinskiy, Henrique, Alexis Sanchez
= success rate: 25%
** I didn't even count guys like Halilovic here
Players aged 23-24:
Success: Ronaldinho, Etoo, Marquez, Jordi Alba, Yaya Toure, Fabregas
Not good enough: Paco, Afellay, Song, Douglas
= succes rate: 60% to get a starter/world class player
Players aged 25-26:
Success: Deco, Dani Alves, Mascherano, Rakitic
Not good enough: Milito, Adriano, Milito
= success rate: 57%
Players aged 27-28:
Success: Guily, Belletti, Abidal, Maxwell, Luis Suarez, Van Bronckhorst, Edmilson, Van Bommel, Sylvinho, Keita, David Villa, Cillessen
Not good enough: Ibra, Hleb, Ezquero, Gudjohnsen, Vermaelen, Arda
= success rate: 67%
Age 29-30:
Success: Henry
Not good enough: Zambrotta, Rustu, Mathieu
= success rate: 25%
Age 31 and older:
Success: Bravo, Thuram
Not good enough:
= success rate: 100%, but too small sample
So, you see, it is EASY to say: we should buy players aged 20-21-22 since they can stay here for 10 years, and they have a good resell value.
In practice, stats say that only 25% of young players whom we bought turned into starters.
We had much more success with players aged 23-24 and 25-26.
So, imo, if we want a long term future, our safest bet are players aged 23-24-25-26.
And if we want short-term success, we are usually good with players aged 27-28 also.
With players aged 29-30 and similar, our success rate is dropping again.
That shows that it is very risky to buy youngsters who had 1-2 good seasons (especially from weaker leagues).
Also, we weren't too successfull with old players (29+).
In terms of superstars, age 23-24-25 is usually good because those players have 3-4-5 world class seasons behind them.
So, they are both already proven (and not one season wonders), plus they still have 4-5-6 years of top football infront of them (and usually 3-4 years in their prime).