Change Decay System please
There must be data related to how many matches it takes to get a reasonable estimate of rating. I think implementing a minimum number of matches to qualify for leaderboard would help this situation. Decay is definitely too lenient, but I would hesitate to make it very harsh to address this problem. Anet wants this game to be accessible to the casual players, and alienating them would only hurt matchmaking in the long run.
Yeah, I feel like simply increasing the number of placement matches would suffice. Or keep decay like it is now but decrease the amount of decay you recover per match significantly.