You can assign only generic stadiums. All licensed ones are glued to one team that originally plays in that stadium. Like you cant move Old Trafford anywhere, only Man United can play there in various modes. So it leaves only with few options for all other teams in entire game. This is why many people asked rather for generic, fake stadiums, that dont require licensing, many of those who Konami had made by themselves, but all of them just vanished. Now, just converting/puting a bunch of stadiums back to old gen would be really cool, seems to be not that hard too. But... They always mention that due to limited time and resources its not possible this year. Then, now we have PES for next gen. Lets be realistic, people paid more money for it, they cant even put optionfiles or emblems into it and now they would be left with like 17 stadiums and we, old gen users, would enjoy baths of old, converted stadiums who dont look that shiny and sharp as in next gen, but are still perfectly playable. No, it wouldnt be fair. Plus, in any case they still wouldnt do that, because of limitations mentioned above. I think EA is pulling people towards next gen at any cost, because FIFA 15 on old gen looks somehow downgraded and KONAMI, I have to tell, released a really great game for PS3 and Xbox 360. Graphics are a mile better as the gameplay itself. So, at least thanks for that. We still have what to play.
