Shaman Pets

[Questors]

I have noticed when I get my max DPS, 55 (spell) pet, 52 dmg, they appear to consistently take more damage from mobs. The 47 and 49 damage pets appear to consistently take less damage from the same mobs.

Is this something to effect of more melee damage equals a more DPS styled pet and less damage equals a more tank-ish like pet? Further example: Rogue = DPS but lower tank ability, whereas a Paladin = more tank ability but less DPS. (?)