It depends my friend, because there are a lot of players that are overrated and underrated as well, so it becomes essential to change some stats.
For example, Alan Smith for me is one the most overrated guys in the game, as usual, and you should change his stats because he is not that good.
On the other hand, we have guys that deserve a lot more, check out Adu and Di María i.e., they are very talented and a bright future ahead, and they are rubbish. David Luiz is a great centre-back too, but his stats are just hilarious.
EDIT: mizta you have the bin/cue file here: http://files.filefront.com/999mizta999OFv15rar/;8927453;/fileinfo.html
Or you could check out Arsenal, incredibly underrated with its stats.
Compare that with say, Barca? I mean, great team yeah sure, but a bit overpowered no?