Are you doubting the capabilities of Sasuke? It sounds to me like you're assuming that Sai could really have killed Sasuke. If that were the case then there really is no hope for Sasuke -.- at the very start of Shippuden.He didn't even really protect Sasuke from Danzo, because he sent Sai to kill him regardless.
Too much holes in this character you are trying to justify somehow, it is not even funny :drive:
There are holes because Kishi hasn't filled them all in yet -.- At the end of last chapter it seems that he plans on going into that whole situation, finally. Besides Sasuke doesn't blame Itachi for it so why should you?
@ Uchiha Defender I'm not arguing the fact that the coup was right or not. Though it is easy to see why they would want to. Their power was cut, but they should have done it from the start when Madara wanted to. They had a strong leader and they missed their chance.