He's only worth what someone is prepared to pay for him. He's really had an underwhelming 18 months, well below the standard we know he's capable of. He's worth nothing (to us) in 12 months. He gives no indication that he wants to be here. We could pay 2 new players if we get his wages off the books. All these things count.
You may have noticed that shops have sales every now and again. It's so they can raise some cash from goods that are just taking up space in the showroom or warehouse. The retailers clearly think they're "worth" more, as they originally wanted a higher price, but they weren't selling any or enough at that price. So they sell at a lower price to make space and get cash. All the supermarkets have 'yellow sticker' items when perishable stuff is close to its sell-by date.