So here's Diego Costa apparently confirming, maybe, that he's coming to Chelsea. Maybe. It appears to be a radio interview that's been put to video for easier mass consumption. Though we might need a stethoscope and some CIA-level equipment to truly be able to hear the question and answer about Chelsea.
Here are a few translations I've found for that crucial last bit:
Reddit: "It does seem like I will [play for Chelsea]." or "It may happen." or "It's possible." or "Maybe."
Inside Futbol: "Yes, it could happen."
AS, and just about everybody else: "(Well), it looks like it."
That may just be an exhaustive list of all the possible translations of 'puede que sí.'
So he's saying there is a chance. Probably a good chance. There is a chance that it's a good chance. It's possible that there is a chance that it's a good chance. It could be possible that there is a chance that it's a good chance that Diego Costa is coming to Chelsea.
So that's settled then. Maybe.