Comparing KC DMG with same amount of casts

[alpine mural]

We're currently on heroic Mug'zee and our DMG is looking low. I have a log with comparison to another hunter that killed it. How come their KC DMG is way higher with the same amount of casts? https://www.warcraftlogs.com/reports/compare/GNHwcxpWrAvyqf92/9QqC2rJLkYRN1GzZ?fight=65&type=damage-done&start=98657560%2C13303059&end=98953031%2C13598530&source=7%2C24

[fair matrix]

hes has 3 more ilvl than you on weapon

his trinket all boost stats, which help KC

yours is pure damage and both have 0 agi (1 proc it, other has nothing for it)

You're still using legendary skipper which in general will be worst for more consistent damage

5 gems vs 7 for him