G’day JMC
No i haven’t seen that article. Yes agility is specific. However, there are many factors that affect agility on the rugby field. Now in a warm up situation or if a player is poor in movement ability then i think they can work on this in a more closed setting. e.g. accel/decel mechanics, the abilty to plant & cut. However, for players who have good movement ability then there is better transfer in performing agility in specific conditions where they have to improve their reaction and decision making ability to different visual cues.
Cheers
Damian