League demotion criteria

[bmike]

I just beat someone and got demoted a league.

I'm curious how often this happens - what the criteria are for promotion / demotion and how a win could trigger a downward evaluation.

I've stopped looking at the leagues for much other than a rough guess - but still, it seems odd so I wondered if this was covered anywhere or there was some reasoning about why/when a change happens.

Does it get calculated periodically and the next game you end is the avenue for the code to check for a league change? That's about the only explanation that makes sense even though it seems a little counter-intuitive. (And if so - perhaps the promotion/demotion would come outside any one game's ending in a future build of the game) Although my game badge still shows the old league so perhaps this is the server getting rectified / rebased / whatever in preparation for the new season?