So the entire time Itachi was under cover he never figured out who the leader was. or how his
power worked.Instead of giving that eye to Naruto to counter sasuke he could have used it on Nagato, or simply
on tobi himself. Pein attacking the Village was Itachi's Fault. he couldn't save the village, Couldn't do jack for his brother but kill his parents.
Itachi= Worst spy ever.
Atlease Sakura sets out to do something and gets it done. She becomes a healer and Boom she heals. Itachi becomes a Spy and fails at that.