Here's the wording on the terms of the Chase 10% discount:

"To take part in this promotion, eligible participants must log in at www.ba.com/Chase10, make a roundtrip booking between December 11, 2012 and December 31, 2013, and enter the promotion code provided in this offer into the marked box on the Price Quote page of the booking process. Offer is non-transferable and cannot be combined with any other offer. Outbound travel must commence by December 31, 2013. 10% discount will appear on the final payment page. Discount is valid on the total roundtrip purchase price, including taxes, fees and carrier charges, on mainline flights operated by British Airways."

Is it reasonable to consider an Avios upgrade using points as 'another offer'? It's not as though it's reducing the ticket price at all.