Brang (a well known hunter class player) has released a new video explaining the PVP hunter mechanics at level 85, what pets to use. Here is the crab that got the Intervene ability reworked.
Crab Talents Spec
It now denies the damage taken by a target (you) by 50% of his health. With Last Stand and Great Stamina talent, the crab can save the target for 90.746 damage and 67.080 damage without Last Stand.
Intervene now has 30 seconds cooldown, Last Stand has 6 minutes cooldown. The only issue is that the crab still requires a small range to cast Intervene. Send the pet to attack the target while staying at distance.
Crab Intervene Macro.
/cast Last Stand
/cast [target=mouseover,nodead,help] Intervene
/cast [target=player] Intervene
/petattack
The Pin macro is simple: /cast Pin
At least in battlegrounds, the crab can be a better choice instead of a monkey since it will protect against dots, in a 1v1 encounter can save a lot of damage at start depending on the enemy class.