[Pokerlogist]

I checked and they say that "the bad beat and winning hand must make use of both hole cards." So that part is okay.
I believe the thrown away hole cards are the issue. If, for example, 50% of the potential BBJ hole cards are thrown out in real play then the probability of winning it is pretty much cut in half compared to the showndown probability in the OP. I don't have a reliable estimate of what the actual "folded BBJ hole cards" percentage is right now.