Connolly probably should have stayed in Junior but I guess Tampa really didn't want him staying in Prince George.
Neidderreiter is a case that probably helps your point. He was a very good junior player, but his 70 points in 55 games didn't really indicate that he was above and beyond the level without question. Keeping him in the NHL with minimal ice time probably didn't do much good for him.
Grigorenko though, like Galchenyuk, seems to be more advanced than Nino was. He had a better point per game ratio as a draft eligible player than Nino did after being drafted. He's on a tremendous pace right now near 2 points per game in the Q. That's a bit of a step up from Niederreiter or Connolly