I hate to say it, but apart from the game styles being different and maybe taking some time to get used to, I just think it comes down to how much these signings apply themselves as to how well they go in Superleague?
The "no name" aussies Mr C mentioned come feeling it's an opportunity to prove themselves and develop their game, and hence plug away consistently and earn the rewards. Maybe other guys who were first grade NRL standard sometimes come over and don't have the same motivation to develop on their games, mentally clock off and represent poor value signings for their clubs.
If I was recruiting for a superleague club, I wouldn't worry about established/older first grade NRL players too much. If there was a need to use the import quota places, then I'd be looking at Premier League for guys who are being held back behind some star players in their chosen positions. Get them guys over cheaper than name stars, and watch them champ at the bit to develop and be good value.
But as has been said there's plenty of locals in the English game with the same motivation and value for money, who should be able to get the chance to develop their games to the next level.
