They may have settled at a %There must be something missing from this story... nobody in his position would just give away the rest of such a lucrative contract. As @FoldingStars says he must have something lined up already on the basis that Chelsea take a bit of a hit with a payment to him to end the contract and he gets a contract elsewhere which basically means he's not out of pocket and has an opportunity to play.
We pay you 60% now or you stay and sit on your arse for another year?
May also mean they take the financial hit immediately, in a year they think they have headroom?