TTT will be a better 3rd single. I'm not saying YDO is a flop, but with WFL going so strong, YDO won't be doing anything major for album sales, although Def Jam probably planned that. Urban buyers haven't been exposed to anything really 'urban' yet, and TTT will change things. If WHYB was released as the next single, all the urban buyers would probably assume the rest of the album is just House/Pop/Dubstep songs and not really bother buying the album. This era is still new, so the change in sounds for the next single will be critical to appeal for all audiences.
