In what Nate Silver is calling the worst damage control effort ever, the Guardian Council admitted that the votes collected in 50 cities exceeded the number of eligible voters in those cities, "only" affecting 3 million odd votes.
Even given that the reported turnout was a historic high - over 80% - that's an indication of fairly massive fraud in those cities. While local turnouts, counted by the number of ballots, of more than 100% necessarily imply fraud, it is not necessary for the number of votes to exceed the number of voters in order for fraud to happen - and to do so is a strong indication of the strength of fraud in those cities. If turnout was about average in those cities (and actually a historic high of ~80-85%), then fraud accounted for more than 15-20% of all votes cast in those cities.
And if that figure held in many areas - with or without red flag overturnouts - turnout may not have been at record highs, and we're seeing the sort of degree of massive falsification that could swing an election so dramatically. And if the Guardian Council is admitting that massive fraud happened, I think the case is now quite materially convincing that the sitting president cheated. Not only that, but that the cheating was extensive enough to make a difference.
If I am convinced that fraud was indeed definitely present, and of an order of magnitude large enough to potentially swing nearly any contested election, I doubt that supporters of the opposition are anything but convinced that it did swing the election, and I hope that a peaceful runoff election, rather than violent revolt, is the outcome of this.