Padraig
The decision has STILL not been made. The guys who have been invited to selection would almost certainly be in the Part Time Part Year 50 contract (PPY50). They work all summer and 50% of the winter. It's a bit more complex than that but yes, it comes out at about 80% for various reasons.
As I explained above, the Hold Pool will almost certainly come in to fill part of any additional requirement SHOULD it materialise, these other guys are a top up if the requirement exceeds the 6 in the pool.
As you say, until the decision is made and only then if there really IS an additional requirement, patience is the only answer!