OH advancement: 10% mission buff if Minions

[Sounder]

Given reports that all gear upgraded by our left-side tier 1 advancement will be replaced within days of hitting 110, I decided to go with the right-side choice.

Still, I cannot fathom why our tier 1 10%-to-first-mission upgrade is 1/2 of most other classes' 20%, ON TOP OF being restricted to just missions with minions, where most other classes are just a straight 20% on the first mission (per wowhead). Has blizzard spoken to this? Does anyone understand it?

Charitably, maybe better mission success is baked into our OH in other ways so it balances, but it would be nice to know that somehow.

Additional question -- is it +% on the first mission of the day (if you send minions), or is it +% on the first minion threat mission of the day? (in the first interpretation, if you do a mission without minions first, you forego the benefit that day.)