I dont mind changing the stats, if they are completely wrong. like Robben's stats and Fabregas etc. Konami doesnt know EVERYTHING, so if they get a few players wrong, we have the ability to change it; that's what it's for!
But I am realistic when I change these stats, so I wouldnt give Nistelrooy a star for this offside thing, as he IS very often ofside.
But to just rule tampering with the stats out completely, because Konami has 'supposedly' done very much research etc, to me, is a BS argument. It's very clear that not every player has the correct stats. It would also have been impossible to expect that from Konami, as there are thousands of players in the game.
If you want this game to be realistic, then you should also be realistic yourself, and edit those stats that are NOT correct. And not just making players better at some things, but also making some players' stats worse when you feel the stats given to them, are too high.