As an addendum to the recent Arena system FAQ posted on the forums, Kalgan addresses several concerns about the gear, the system, and questions of skill vs. gear. In a very forthcoming and transparent post, Kalgan admits that Blizzard "botched the ilvls" of the current Deadly Gladiator weapons by making them a full tier below the items from Kel'thuzad in heroic Naxxramas. At the time they designed them, Blizzard didn't account for how easily accessible Kel'thuzad would be.
He promises they won't make the same mistake in Season 6, and that the new Furious Gladiator weapons would be equivalent to the items in Ulduar. Kalgan explains that the aim is to balance the accessibility of the items so that the number of raiders who have access to the best raid weapons is roughly the same as the number of Arena players with access to the best PvP weapons. He even goes so far as to say that Blizzard will make two tiers of PvP weapons if necessary. This might have been in the original plan as Hateful Gladiator weapons are in the game files but not available in the game.
Kalgan also explains that the Matchmaking Rating (MMR) is hidden because Blizzard didn't want to confuse players with a third rating, particularly because players don't need to make decisions based on the MMR. Players only need to know their personal and team ratings to know if they qualify for the purchase of an Arena item or how many Arena points they'll earn for the week.
Finally, he shoots down arguments about Arenas being a place where gear is the determining factor for wins or losses. He's quick to point out that the same players who dominated the Arena realms, where the same gear was available to all players, are the same players who climbed to the top of the ladder in live realms. Skill, he says, is far more significant a factor in success in Arenas more than gear or team composition.