The St. Louis Blues had a lot of faith in David Perron when they drafted him in 2007. If they did not, they would not have put him in the NHL immediately and play him for 62 games.
Unfortunately, as with many young players, the talent never quite showed itself the way the team and the fans kept expecting. There were glimpses and flashes, but not always there the entire time. That is why the Blues traded him.
However, members on the staff always kept hoping he would truly shine in the blue note. That is why they kept bringing him back, after a trade and after being taken away in the expansion draft.