10 matches for placement is not enough since a DC in your group still counts as a match and a loss, realistically there should be at least 30 matches required for placement this would create better average.
This would more accurately place people in there correct division meaning when they cue they get people who were accurately placed and not some lucky streak fluke.
As for 2 max in a group this causes problems since they are often forced to play with compositions that are weak even If the players are good since ranked in season does not allow people to form full teams which are either made up of friends or guilds