I honestly don't see the problem here. You had the same ratings in scoring (actually you were slightly worse), and he had better defence. What's to question here? I don't know where someone got that 80% estimate from, I'd say that since you had HCA and got GDP right, that maybe makes it 50-50.
If you look a little deeper, it's a little surprising that you won the 4th Q, given his players got a lot more rest than four of your starters, who played almost the whole game. Then again, it's also odd how poorly you played in the second ... but overall, not at all a surprising result given the ratings.