Lets be honest with ourselves for a moment.
I won't blame Ranieri and I won't blame the players either.
We might be the only team in Serie A who has played the whole season's games whether Serie A, Coppa or CL with the same starting eleven +/-2 players.
In the past 10 days we played 4 games all with the same players.. The players are extremely exhausted.
Legro is a very good defender, he was controlling the defense in the past 2 seasons well (alongside chiellini). Sissoko is not a well passer but his work rate is great. Marchionni is running up and down the field every game. He might not be as talented as Camoranesi but he is well worth every penny we are giving it to him. Del Piero and Amauri have featured in almost all games as well and we have are one of the top scoring teams in the serie a.
Our problem is in our medical and health staff.. Most of our injuries happened in the training grounds. If we had our full team +/- one or two injured we will definitely be in a better shape.
Now, on the Molinaro issue

lol .. Well noone can question his work rate. BUT he doesn't cover his position at the left flank well. You find Legro many times covering for him. His crosses are terrible and he doesn't position himself well.
DC might not be a great defender but he is much better when it comes to crossing the ball.