I guess I've found out what happened:
Obito was about to die, then Madara (that was Tobi in that time) rescued Obito, trained him, and instructed him to do his will... follow his path...
Was Madara who started everything, controlled Mizukage etc
Then, when Tobi fought the 4th, it was already Obito with his new skills and Madara was dead (well, even the third was old in that time.. imagine how old would Madara be)
I think that in next week I'll be the one saying: I told you so!
PS: Poor Obito... when he got his promotion to Chuunin, Rin instead of saying: WOW YOU DID GREAT, prepared a party for Kakashi's promotion.... I guess the storyline will be awesome if goes as I'm predicting