I think you're confusing 'biggest upset' with 'I got upset with the result'.Jon jones beating Cormier gets my vote, though rockhold beating the chris is close.
yea those odds were at something like 12 to 1 at one point. Dropped down to around 7 to 1 by fight time.Holm vs Rousey has to be one of the bigger upsets in MMA history in terms of betting odds. Since everyone thinks Rousey is completely horrible at fighting afterwards it retroactively undercut just how surprising it was to people at the time.