Tweaking the stroke

This is a picture my coworker sent me yesterday, critiquing my dragonboat stroke. Things to work on:
1. "reach more with top arm"
2. "bury the blade before pulling"
3. "rotate more to keep hips under torso, so that the lower back doesn't support the weight of the entire upper body lean"

Someone could have told me about 3. earlier. My back's still all jacked from Tuesday's practice.