Certain classes have skills that have minimum abilities.
For instance, a Paladin will Autotrain in Slash and Chants only. If you level up,a nd don't put any skill points into those skills, then they will always level up to 1/4 of your level (so at level 40, you would be 10 in each, even if you didn't do anything ot them).
It is a stupid thing they executed trying to make your toon not worthless, but all it does is make toons that get Powerleveled slightly more powerful then toons that level regularly.