Possible arena tier idea
So, one of the biggest complaints people have with arena matchmaking is that they feel they are matched against players they have no chance against. What if, rather than matchmaking being based exclusively on your arena rating, you were also put into tiers based on your account age? Here's my basic idea. Divide the playerbase up into six tiers (for now). More could be added as the game gets older:
Tier 6: All players
Tier 5: < 2 Years in age
Tier 4: < 1 Year in age
Tier 3: < 6 Months in age
Tier 2: < 3 Months in age
Tier 1: < 1 Month in age
Players are matched up against only players of their same tier. So if you are a player who has been playing for more than 2 years, you'll be in Tier 6, and your arena pool will consist of all players, while if you are only five months old, you'll be in Tier 3.
However, if you are matched up against a player who is in a lower tier than you are, while you'll still get points for winning, they will not lose points for losing. This avoids the problem of having a too-small pool of players for the older players.
I'd suggest having the tiers be plainly visible and clearly explained, to avoid having players be caught off guard when they are automatically moved up a tier after their account ages.