Sinking and rooting provide an inherent use of gravity.
Dropped shoulders, elbows, sunk hips and relaxed spine, knees and ankles improve root.
Without root, you are 'floaty' and weak.
Additionally, you must weight shift with every striking movement except for kicks.
If your weight is not behind the movement, where is it?
When shifting weight, the alignment of the pelvis, hips and knees must be considered.