My two cents on arena rankings / difficulty / etc...
I feel that, by far, the biggest problem is that we have no "easy" way to determine how well our team will do versus the opponent. And that's normal - it should be a challenge.
The problem is that the contribution to team score that speed provides is incredibly low. So you can have a team strength of 100k winning against a team of 250k, simply because the glass cannon speed nuke team will act before the other team can do anything.
That in and of itself isn't an issue - what is, though, is that you have no way of knowing if that 100k team is a speed nuke team, or just a normal weak team that you can beat.
My suggestion - double, or perhaps even triple the amount of team power that speed contributes. Getting 250 speed is not easy, getting 300 speed even less so, and 350 requires some very good gear to accomplish. But because of how low the rating derived from that is, you end up looking like a much weaker team than you actually are.
Also, ban Hegemon and Tormin. Nobody likes them. (jk)