Win rate should be reset when changing Tier

[Nettogrof]

During a league (lie summer league) it would be nice that the win rate were about in win rate in the current snake tier.

Currently Pretzel join the summer later than most of the snake, so Pretzel had to beat a lot of low tier snake to reach the top, making the win rate irrevelant if compare to Pruzze one.

[bvanvugt]

Yeah, this is a super good suggestion. Not sure we'll be able to make this happen before Fall League, but it's definitely something we'd like to do.