I've said it a number of times on these boards about overseas signings, yes quality and attitude are high on the must have list but you also need a lot of luck. With the NRL being the only real over seas market (unlike football or even RU) you never know how players and their families will react to moving half way round the world to a game that is called the same but played differently.
Also, for a lot if us SL fans we see very little of the NRL players, often at best the occasional game and highlight reel yet we are quick to slate players for being this or that when we have very little idea what they really are all about.
I remember the signing of Kylie being met with a very luke warm reception yet look how he turned out. Brent Webb was rightly met with great excitement and he fulfilled it. Brett Mullins was also met with excitement but never showed his NRL form, but then rekindled it when he went back to some degree.
Lady luck does play get part.