Leaving a league

After the release of Heart of The Swarm, a feature was added in the league ladder section, where you now can leave your current league. I noticed this in the BETA aswell. In the buttom right of the screen, when you are at the "View Ladder", theres a button that says "Leave League".

• What is the purpose of leaving your ladder league in StarCraft 2?
• Will your MMR remain the same?

These questions rise when I see the buttom. And wonder why some would use this. And if the MMR is the same, why leave just to join the same league again.

Your MMR will stay the same. It is not known what happens to MMR confidence, but it may well just not come into play, as the game will need to place you somewhere (a low confidence value does prevent you from being promoted, even when your MMR is already in another league).

So, in general the purpose is to force re-placement into a league, if you believe you're not where you belong. That is when you're tired of waiting for a promotion, or, arguably more importantly, when you are too high. Since some recent version it is impossible to be demoted mid-season, only to re-qualify to a lower league.

On one dull Friday night, after several vs.AI matches and some three liters of beer, I had a brilliant idea - go qualify in 1v1, so I will get placed low and play slow and peacefully. I was pretty drunk, and played Random. After four proxy 2-gates and one 8-pool vs a Master leaguer, I was left with Hot Shot, in Platinum, and an expression like O_O.

After getting brutalized in Platinum for a couple of days, I've left a league and found my place in Silver, and all was well once again :-)

From a post I found on the Official Forums:

So.. say you're in Bronze, but you've won about 100 games, quickly, in a row! The Blizzard matchmaking system is confused, as it doesn't know if you're getting lucky, or you're really good... So, when you press the Leave League Button, instead of having to lose games to get your MMR stabilized, when you press it, it acts like a new season has just started, so therefore, you can just do a placement match, and get placed into the league of what your current MMR is!

So to summarise, it appears to force a recalculation of your current league placement, by making you re-play the placement match, like when a new season starts.