I don't know about the 50% mark, but at some point it becomes true. When I was in college, one of my friends was big into MMA, to the point of participating in organized fights and maintaining a winning record. He was wresting with another friend (much larger and stronger, but not at all involved in MMA) on one occasion and learned rapidly what raw strength does. The MMA-participating friend was completely outclassed. Everything he tried was basically just beaten with brute strength. He attempted to put the larger guy in an armbar and the larger guy basically just did a bicep curl with him.
You're also underestimating the strength difference between women and men. Pound for pound, an untrained man will be about 50% stronger than an untrained woman. With both trained, the difference approaches 100%.
http://www.exrx.net/Testing/WeightLifting/StrengthStandards....
Edit: Whenever I hear comments about women beating men in physical sports, I think about the Williams sisters both losing to the 203th ranked male tennis player, who supposedly didn't try very hard, and according to some reports spent the morning before drinking and playing golf, and smoked between sets.
https://en.wikipedia.org/wiki/Battle_of_the_Sexes_(tennis)#1...
http://www.yourememberthat.com/media/15978/Karsten_Braasch_v...
I seriously doubt that the 203rd ranked male had better technical skills than the Williams sisters. Skill only gets you so far, though.