That unfortunately is wrong. Now I don't know exactly how it runs with the world junior team, but I can tell you there is tons of bullcrap on the Team Canada women's club. One of my best friends played on that team and won a couple of gold medals to boot, and she's told me of the b.s. and politics that goes on.
Such as Haley Wickenheiser outright violating the "no contact sports" clause by playing in a men's league in germany. Players are not permitted to play any contact sports to be considered eligible for the national team. Yet she goes ahead and does it, and is allowed to play still.
Gillian Apps is one of the most atrocious monstrosities ever to lace up a pair of skates. She's slow, can't shoot, and can't even honestly handle a pass. Go ahead and watch some of the previous women's games. She can't handle a pass. Only reason she had one great olympics was being on a line with Wickenheiser and Piper. Yet because her daddy is Syl Apps (I think he's vice-president of the national women's team, or close to it), she's on the team. There are plenty of 18 year olds that could skate circles around her, but she's on the team because the coach has to make the "right picks" to get the job.
Those are just two examples of how the whole "the best players play" is untrue. Like I said, I don't really know the inner workings of the world juniors team, but if it's anything like the national women's team, there is bullcrap, politics, and favoritism.