It's pretty important. Showcases most of the skills necessary for rugby and needs to be well balanced. 6 a lineout option, big carrier, big hitter and smashes rucks. 7 link man between backs and forwards, slighter than backrow colleagues, usually a fetcher and vital for your own rucks creating quick ball. 8 old school big strong guy for making yards off back of scrum i.e.Chabal, Jones. New breed athletic, all over the place, considered to have a bad game if they don't make a 40 yard run, ball carriers, lineout options and generally talismans. i.e.Heaslip, Reid, Parisse. Is this way everywhere apart from France and S.A. where openside and blindside switch numbers. Also Ireland don't really use a 7.
My biased but so good backrow:
6. O'Brien
7. Pocock
8. Heaslip
My biased but so good backrow:
6. O'Brien
7. Pocock
8. Heaslip