The high-level swing is powered by the entire body -- and the large, powerful muscles of The Core -- and not just the hands, wrists, and arms.
In a high-level swing the hips open first and then pull the shoulders around.
I discuss Rotation in this and a number of related essays...
Rotation vs. Linear Motion
The idea that the swing is powered by the Rotation of the hips and shoulders stands in sharp contrast to what many people believe powers the swing...
- A linear, pushing movement of the arms, wrists, and hands.
- The extension of the arms.
However, the fact is that, while the muscles of the hands, wrists, and arms do play an important role in the swing, their job is not to create force; they are just too small. Instead, the role of the muscles of the hands, wrists, and arms is to...
- Help funnel, direct, and manage the force that is generated by The Core.
- Make adjustments based on the location of the pitch.
As proof of this, look at the clips below and notice how much these hitters' shoulders rotate before the bat leaves their back shoulder. That indicates that they are powering their swings with their entire body and not just their arms, hands, and/or wrists.
Jim Edmonds' Rotation
Jim Edmonds' Rotation
Megan Bush's Rotation
At most, what these hitters' hands, wrists, and arms are doing is maintaining the position of the barrel relative to the shoulders.
The real force is being created by -- and the true engine of the swing is -- The Core.