Wow, the iwg2 stats conversion is quite complex. I can barely follow most of the stats adjustment stuff, but I think it goes like this:
Initial "multi-classing" penalty for fighters over level 4. Those levels are redistributed into Fighter/Bard/Rogue.
Class bonuses. This un-does the penalties above. The bonuses are applied for each element in a class/level array (allowing for more than one bonus for the same class dpending on how the list is built up).
The attributes so far are actually only used to determine how the attribute points will be distributed from a total fixed number of points. A new set of attributes is initialized to all 7's, and 34 new points are added to (more or less) match the distribution.
Finally stat racial adjustments are made.
Here's an example of what happened to a 1HD fire beetle from IWD1: The beetle's stats from IWD1 are all all 9's. The beetle has one level of fighter which gives it a +4 for Str/Con/Dex. So now the rank ordered stats look like this:
STR 13
CON 13
DEX 13
INT 9
WIS 9
CHA 9
Now a new set of attributes is initialized to all 7's, and 34 points are added according to the above distribution resulting in:
STR 17
CON 16
DEX 16
INT 9
WIS 9
CHA 9
Wow, that's some bug!

This bug is supposed to be a monster you deal with at the very beginning of the game. At this level, those stat bonuses make a big difference (+3 HP, +3 AC, +3 damage I think). As a comparison. here are the stats for a 2nd level beetle (a summon is all I could find at this level):
STR 11
CON 11
DEX 14
INT 4
WIS 12
CHA 9
A Targos Gob has these:
STR 8
CON 11
DEX 13
INT 10
WIS 11
CHA 8
So I'm beginning to think that a better way to assign stats is to profile the creatures in IWD2 and create a table (with some interpolating where neccesary). The method in iwg2 would be great if you wanted to create an army of adventurers to go up against the party, but I don't think it works for monsters in general.