This 3% probably happens towards the top of the leaderboard, when a legendary/high platinum player can’t find a team to play with, they get some substitute. Where there’s a high pool of players queueing simultaneously, a substitute doesn’t make a great difference, but at the top it could be difference of 200-300 rating because there are 250 players within the 2100-1760 range in NA. Thus we get matches that are completely one-sided.