Please can someone explain the logic here, because I truly can't see any?
It's an honest question, not having a pop, just can't see why you would give a 17/18 year old kid his Super League debut, then dump him into the Under 20's the following day.
I believe there's an RFL rule which says a youngster can't play 18's and 20's in the same weekend, so maybe there should be one to cover all grades.