DoTA is a better version of WoW’s Arena PvP?
Set map, 5 v 5, class/skill/item balance dependent, fairly twitch based, team unity/communication being key…
Seem fairly similar to me, other than the fact DoTA is 100% fair pre-game, while the outcome in WoW is pre-determined 99% of the time before you queue (gear).
Blizzard should just do what they normally do, copy something successful and call it their own.
Hardcore Casual 
I disagree with the assessment that wow arena is 99% determined based on gear. Unless you’re talking about 1600 level or something, most people will have full access to the same gear, with the notable exception of top-end pve gear such as the Warglaives.
We could argue all day about how much of an advantage pve gear is – and in certain group comps it definitely IS an advantage – but it certainly doesn’t come close to 99% determining the outcome.