That is hard to say as there is a lot of factors at play. Matchups is a big one. If the guy that is marking him is good, he can be kept to really low points and alternatively if the guy marking him is crap, your player might have a point explosion. Likewise, a player that averages 25 points in D4 could find it hard to even put up 15 in D2, etc.
In order to play this game successfully, I'd suggest not looking too much into the stats as these can be influenced by a lot of factors.