What is an "assist"?

From the JEA:

Physically assisting implies that the coach did something by touching the runner which improved that runner's chance of accomplishing his goal as a runner. In other words, touching alone does not constitute physically assisting. The umpire must be convinced that the runner is trying to get back to a base or is trying to advance with a sense of urgency.

I argue, then:

• The coach gives his runner a congratulatory pat on the butt while the ball is dead. Not an assist.
• The coach and the runner collide accidentally. Not an assist.

Barring those events, though, any touching is physical assistance — interference — and the "touched" runner is out.

Continued...