Currently how high your deck gets rated is extremely dependent on getting as much plays in as little time as possible, more so than actually being the most evil arena deck. Hence after discussing in chat I'd like the decay of a deck to be more dependent on the amount of plays a deck gets and not the amount of days it's up. Otherwise a great deck you built never reaches higher than 100th ranking for example before it hits 1 hp, although it never lost.
An example would be to let each play subtract 1hp from your deck and maybe even let your deck be removed from arena when it reaches 0hp to prevent decks from being built that can win even with just 1 hp (they exist!). This way good decks no longer have to get their plays asap in order to be ranked high, and building new decks each day is still encouraged due to the slowly decreasing hp.
It's just a suggestion, but I'd personally be happy with such a case: a high ranking in arena shouldn't be dependent on the luck you have of getting plays in a set amount of time, nor by timezone, another point that comes to my mind, since people sleeping during the oracle reset have a natural disadvantage over people submitting their decks at the oracle reset currently.