In August 2016, at the start of next seasons 2016-17 campaign.
Attack:
Messi: 29
Suárez: 29
Neymar: 24
(We don't need another striker. Arda can be subbed in for Neymar, Rafinha for Suárez & Roberto for Messi.)
Midfield:
Iniesta: 32
Arda: 29
Rakitić: 28
Busquets: 28
Roberto: 24
Rafinha: 23
(We don't need another midfielder. Iniesta & Arda can rotate. Rakitić & Roberto can rotate. Rafinha can be our back-up if someone gets an injury and Busquets, well, it's Busquets, nobody touching him. But if needed Rakitić or Roberto can step in, should he get an injury.
Defense:
Alves: 33
Mathieu: 32 (almost 33)
Mascherano: 32
Adriano: 31 (almost 32)
Vermaelen: 30 (almost 31)
Pique: 29
Alba: 27
A. Vidal: 27
Bartra: 25
(Sell Mathieu and Adriano and buy a new LB) Piqué & Bartra can rotate. Mascherano & Vermaelen can rotate. Alba & new LB can rotate. Alves & A. Vidal can rotate, but since Alves is getting old, maybe Roberto should get some playing time as a RB?
The way I see it, we only need a new LB