Each staffs have different ways to handle reports so they have different perspectives I think.
The unofficial rules emphasize that step of rules interpretation:
23. When deciding if a user has broken the rules, the staff have the right to follow their interpretation of the rules.[e]
There are some answers for this question, I found:
For example, I've learned that leaving reports unhandled is the best thing to do in certain scenarios where as before I used to assume that was bad, and you needed to handle as many as possible.
Unhandled reports basically just mean there has no action been taken. If a report has been sat there for a few days, and its still unhandled its likely that a moderator couldn't decide whether the report was correct or incorrect. They are then considered as "soft" bad reports, but don't impact your percentage. There can be a variety of reasons why the report hasn't been dealt with, but usually because the staff members are unsure what to do.