Absolutely, the squad is too big. Inzaghi has been comfortable fielding primavera graduates like Murgia and Lombardi, anyway, so there's no need to have this many senior players.
Having said that, one reason that some players have got so little playing time is that outside our defence, we haven't had that many injuried this season. We won't be as lucky all season long, so there will be more need for subs to step up.
But clearly someone like Morrison should be out if there's a team somewhere willing to take him. Leitner, Lukaku and Luis Alberto are still adjusting, but Morrison's been at Lazio for 18 months already and it's clear that he won't play any role in the team.
Djordjevic is a difficult case. He's fallen out of favour but if Immobile gets hurt, we need a proper striker. He might fetch a few million in the market, but I don't think he should be sold unless there's a replacement ready.
Irriducibili? No thanks, I'm a fan of Lazio.