An update for Rainbow Six Siege rolls out today, which should improve matchmaking.
The patch changes the "relaxation parameters for Skill Rank." This addresses the lack of a maximum rank differential between teams, although Ubisoft hasn’t clarified how large the gap can be after this update.
"Relaxation will occur quicker, but with smaller increments and with a maximum differential cap between teams. This means that you could see an increase in matchmaking queue times, but the match up will be better balanced and of better quality," the patch update reads.
It’s unclear how long people will be waiting for matches now, but Ubisoft wants players to keep them informed as to how they feel about the patch.