How do I properly interpret the logs?

Hi! I’m totally new to the forum, but obviously not Warcraftlogs.
When going through the logs from last nights raid I wonder why someone can be higher on perf % and lower on ilvl %, while others have lower perf % and higher ilvl %?

I guess I’m not as pro at reading logs as I thought I was at first, haha, but I would love to get some help with that!


Førest is here 65 % on perf and 46% ilvl while Hou is 39% perf and 60% ilvl. What’s the “best” way to understand how “good” a player is? Perf % or ilvl %?