Maybe the "biggest flaw" not "Major" might have been a better choice of wording.
If you tinker with weighting BBs and HBPs, you change the meaning of the new stat.
I brought up the HBP, because it seems like a stand alone occurrence. Sometimes, it does involve the "skill" of the batter, but usually, it is a mistake by the pitcher.
I guess one could call a BB, 4 mistakes, or even a HR a pitching mistake.