This does not have anything to do with swing or rhythmic structure but steadiness of the perception of time. It is essential for all musicians to develop this ability. Unshakeable time is a trademark of all the great jazz players. The second element is pulse. We all have one, namely our heart beat.
Pulse is an internal phenomenon while meter is an external one.
These two elements need to be linked in order to function in the rhythmic universe. The pulse of jazz is also linked to the element of swing. It has to do with the strength of their pulse. In other words, the jazz pulse must be internalized so thoroughly that the soloist would swing just as hard with or without the rhythm section. When all members of the group lock in on that special feeling, the impact is overwhelmingly strong.