even redeeming on partner metal, BA may profit:

I am working on a 20K flight mile oneworld award and indeed, as BA charges the YQs for partners, the trip cost is calculated as 100K miles + about $750 in taxes and fees (about $550 in YQ, rest in taxes).

The worst part is that for intra europe fares, where the base fare is low, one still has to pay the rather high YQs (on IB, MA, AY, etc.), so the difference in cost between a paid ticket and award ticket is relatively small, but no status or miles accrual is possible on the award ticket. e.g., FCO-MAD on IB costs about $80 in taxes&fees (for Y). MAD-JFK is about $180 (YQ is 100 EUR).

Of the partners, QF and IB seem to have the highest surcharges, with RJ a close third. CX, JL, and AY are not bad, but finding AY for TATL legs isn't the easiest.

How does BA profit? Well, as I understand, the YQ is kept by the ticketing carrier (BA in this case) and not passed on to the operating carriers.

Just my experience so far, YMMV.