Could it be cost based pricing? I rather hope not as it kind of undermines the point of a miles programme for customers: basically, when cash tickets are expensive, but miles are available, they don't expect to sell a full cabin but are pricing high to attract last-minute/high-end business customers.
That said, the great bulk of my redemptions have been on BA so it's not disastrous. It is pointless to say that prices are changing without saying how they're changing though.