rich junco
If you are ONLY looking for the reason why spookie is doing more melee dmg than you are, then it's simply because he was BM spec every pull and you swapped into BM in later pulls that results more pet melee dmg output for spookie.
I do not think looking at overall dmg is something you should focus on, in fact down the boss then look at that log to see what you can improve on your next kill.
wooden oracle
I honestly forgot that I was playing with MM in the beginning. But even so, I did a hefty amount of pull after swapping to BM. I think I have it figured out, he has the CCT trinket (which affects pet attack speed) and had about 5% more haste than I did. obviously some smaller niche things here and there, like 2 ilv difference. more sockets on gear overall, higher haste = more procs throughout the fight.