When you say "always" what exactly do you mean? He has only had one decent season in him in 10 years as a pro. He seems a classic example of a footballer signing a life-changing contract and then putting more effort into his life-style than his profession. I really cannot see what the fuss is...
http://thesoccerguys.wordpress.com/2012/01/01/stephen-ireland-continues-to-fall-from-great-heights/
I really do think he will be a bad influence at the Albion.
You say could become a fixture, it's a gamble just like Vicente was. He could also very easily not show any interest, pick up further injuries or carry on being a knob. One decent season by the age of 26 doesn't suggest much to me I'm afraid.