So, crack open your XPH, and take a look at the Astral Construct. Level 1, we'll start with. BAB +2. Ok, not bad. Wait a minute, 1 HD? BAB +2 at HD 1?

Level 4 has +5 at HD 5, then level 6 has +9 at HD 10.

Wtf WotC. Can you please follow your own rules?