this years draft class is a bit over-rated, personally I wouldnt choose any of them over Morgan. I think what many dont realize is that Rielly is still a bit behind in terms of development losing almost a season to an ACL injury.
His pairings this past year until the leafs acquired Gleason were AWFUL, Tim really isnt that fantastic either. Mark Fraser is likely not an NHL player anymore, Ranger was still finding his game, regularly looking worse than Morgan and Franson was a gong show turn over machine often well out of position and a huge liability.
So when your talking about Trouba being better than Rielly you should remember he was paired with Mark Stuart, Maata filled in on top pairings with the likes of Letang and Nisk so yea their numbers are going to look better but you have to see the big picture.