Tai chi was designed to make your body an effective conduit for the use of kinetic energy.
If your body is stiff and tense, you will not be able to utilise jing.
It is necessary to be soft and loose, sensitive and open.
This does not mean flaccid.
The groundpath must be present constantly, otherwise you cannot transfer kinetic energy from your body to another.

If you are stiff and unyielding, disconnected or flaccid - this transmission will be unsuccessful.