Based upon my research as to the events that have taken place in the Great Schism I have gathered that Michael I Cerularius is portrayed as the cause for the Schism. Essentially what it boils down to in almost every article I read is that if he just had the patience to meet with Cardinal Humbert when he traveled to see him on the Pope's behalf a large majority of this would have been avoided. Granted Cerularius was the one with actual "issues" per say with how Pope Leo IX was performing his papal duties (along with the whole "pope" title in and of itself) in my opinion, I think there are a lot more people to blame for the resulting schism. 

 

One take I have on it is that Cardinal Humbert who was the first to excommunicate is way more at fault for this then articles lead him to be. Granted he had to act on instinct since Pope Leo IX had just passed and his wishes were no longer valid. The act of excommunication is the most severe punishment one can face in the Catholic Church. In my opinion, Humbert should've tried to wait more than a few months if his next best play was the most severe punishment possible.