I don't like Oscar that much to be honest, but i reckon his transfer is a 'market opportunity' as i believe he has been playing less with Chelsea last season, at least during the end of it, was mostly on the bench, even more in CL. Perhaps there is a falling out with Mou, as with Cesc, Willian, Hazard, Matic, it gives little space for Oscar.
Not saying it will go through, i still hope for Isco, but Oscar's current situation and should Chelsea manage in getting another creative player (Griezzman being rumored not sure how reliable the rumour is) does make him a market opportunity, and with us showing our interest early, it can help Oscar choosing us over other teams, should he look for playing time and not $, if that moment finally arrive that he becomes available..