Oppertunism and marketing-reasons would go a long way to refuting that point.
True, but they certainly cant be big factors, its not as unlikely to suddenly have Aguero as an option because he looked good in Copa, he looks good wherever he plays. You either planned/interested to get him from the get-go, or are suddenly because something changed, like you sold a player in his position. Like City would be if they sold Tevez etc.
Thats why we need to do this sooner then later, we dont need variables to change too much in the big clubs, that usually shifts the market alot, one of them sells a player and needs a big signing, and that generally starts a momentum in entire market. Dont need Aguero to become part of that. Though thankfully less likely because attacking departments in big teams are pretty damn set.