Why don't they play for barca anymore?

Why did pep guardiola buy aleksander hleb syedou keita and milito and not make them play? I support barca but i havent really been following la liga this season, how come diego milito, yaya toure, hleb and seydou keita never play? Pep shouldn't let busquets play, instead yaya or keita andhe should take out pique and put milito in theyre way better and possible sub hleb in for toure after a bit and play with 4-31-2.I just want to know, how come those players are benched and dont play?!?!