Good point. I've also been wanting to know if the last year is optional or not. No idea where the information of it being optional comes from. I'm edging towards believing it's until 2019 based on the official site after seeing how other transfers specially state the extra year being optional.
In any case, it would be nice if Rooney really dedicated himself to getting back in shape to see if he could become good again. Those playing football can attest to that frst touch, vision and other abilities are linked with fitness. If you're out of breath you can't even do the simple things well. (At least that's been my experience playing). Don't think he'll become a 300k pw player, but maybe he can be a useful option, would be nice to see.