OP strength is truly on a bell curve, but that curve covers all channeling souls, those currently incarnated, those waiting to be reborn, and those permanently burnt out of the Pattern by Balefire.

If this curve does indeed cover every possible channeling soul, we know that there are millions, if not more, souls that are not currently incarnated, and thus are not being represented in any sample we are taking. We know that in the AoL, there were Billions of people living on the planet, and millions of channelers. We also know that the world's population now is significantly smaller than it was then, and that the channeling population is also significantly smaller in the Westlands because the Tower does not actively search for girls.

Now, deciding if the people in the WoT books actually follow the curve really cannot be done because our sample (living channelers of which we know the strengths) is not random. The Wheel weaves as the Wheel wills, right? The souls currently in the pattern are there because the Pattern has been weaving up to Tarmon Gai'don. Different souls, of different strengths were woven where they are on purpose.

The implication, then, is that the relatively weak channelers in the Tower, and perhaps the rest of the Westlands, are weak because the Pattern intended them to be so.

Sorry for the ramble... I'm sleepy and wanted to post something.