I suppose the "AGility" should've been "Acrobatics" and then his complaint makes sense. Still, It makes perfect sense that a person can have AGL 17 and acrobatics 12 while a person with AGL 12 could have a reasonably high Acrobatics rating. Even though the AGL 17 character has a better basis for learning acrobatics, he (/she) may opt not to learn any cartwheeling, while the AGL 12 character may spend a lot of time in training, not enough to warrant a higher AGl-rating, but enough to cartwheel very well indeed.