* I have been on teams that were not considered the best until they had success, then everyone on the team was a "star".
* I have worked places where they only hire "superstars"-- and were pretty serious about paying for good talent and being picky-- and still failed for all kinds of organizational reasons. Teams with more role players, or more cohesion of goals would have performed better.
*I have seen people recommended because they worked at "X" or worked on the "X" project, and then turn out to be completely underwhelming. Great teams don't always only have great people, and sometimes the great team has people on it who are one promotion away being at their level of incompetence.