Riot gives players lower ranks then their MMR for placements. Partly because demotion protection is a very wide range, something I dislike but they still do as it protects players feelings. You can look at the several years of history where players pool into division 5 and more recently Division 4 after the removal of 5s. So for truly fresh accounts if they did not give lower ranks they when the player lacks that skill level they would end up poolig with the wrong rank for an extended period of time. Basically that Iron player would look like a bronze or worse silver player as that's the rank they would have gotten from placements.
Its my opinion they also do this to add grind as to recover your past ranks you need to put in extra games to bring the gap between MMR and Rank closer. They might be doing it loosely because 10 games with all the variables of a 5v5 team game does not represent high statistical relevance. Probably a bit of both.
Any how the point being the way skill ladders are designed is to give room for players to climb thru Class intervals. A simple way to put it is you leave room for weak players to sink and strong ones to climb.
The problem is that a majority of the protections into systems like this is most of them are directly related to preserving players ratings, rather then upping the quality of individual games. For Example in Elo, you look to refund a player some points when they run into some one overperforming far beyond system expectations. This does not remove the games or stomp that made the system see it needed to refund some one points.
TLDR. Consider Riots Ranks to be complete and utter bullshit till you can see 100+ games.
