I just found this in an FT thread from 2005:
As for a Oneworld-award the price seems to depend on the amount of miles your journey covers. AGP-MEX direct is 5678 miles, and AGP-MAD-LHR-MEX (for example) would be 6582 miles. Most routings would fall into the 5,001 - 8,000 mile category, which costs 3200 points in Tourist (economy) class.
... which corresponds to the above, and to the 48,000 quoted on the new table.
So nothing happened ....?!
Here is the thing. You cannot book OW redemptions online with IB, never could. And as they were non refundable, no-one did. So no-one knew the rates.