so I don`t agree that statistics doesn`t show how good are you at the court...
statistics are an good indicator for the value of the player, but if someone made 3 steals and the other none are you sure he defend better outside? Maybe he calulated more on the steal, and his opponent get some easy basket because he had a bad position after failing in get those steal. You see such defenders from time to time, for stats they are good for teamplay i like the ones more who stay in position.
Player A 20points and 2rebs eff=22
Player B 2points and 20rebs eff=22
also some point where just rating eff are lame, i think 20 rebounds have more value then 20 points. Also often guards ahve lower eff values, because rebs are easier to get then ass.
Player C 20points and 20rebs eff=40
ok he made a hell of a game, not difficult to rule the concurrency with such stats he can not made that much wrong ;)
On euroleague page, i don't have to look if others maybe have good eff values or not, but i am pretty sure that this is not the only factor(winning plays normally a big rule in real life)