Another angle on this – from what I’ve seen more women are being mekarev than men, making the imbalance at slightly older ages even worse. A male baal teshuvah has a chance of being matched to an FFB girl with a “problem” while it’s highly unusual for a shadchan to set up an FFB guy with a BT girl.
And don’t be too complacent about girls not going off the derech. The biological horizon for women having children is middle thirties. We raise our girls to believe that children and marriage are the only worthwhile goal, and then make it impossible for some of them – through no fault of their own – to achieve it, and there is no place in hareidi society for unmarried older women. When the current crop of single women now in their twenties start hitting that crucial age, we may get an unpleasant surprise.