DPS Performance Comparison

So, in every log you have DPS Performance Comparison and DPS Performance Comparison by Item Level. And many times these 2 numbers are a bit different.
My question is in our profiles - how is our DPS Performance chosen?
Because in my profile, I’ve had it sometimes be the DPS Performance Comparison number and sometimes I’ve had it be the by Item Level number. Sometimes it takes the high one, sometimes it takes the low one.
Usually it’s a big deal, but when you get a 100 parse and it shows up in the profile as 99, you lose that achievement.
Just curious if there’s a method to the madness.

Character profile isn’t by item level. It’s overall. Character profile also defaults to rankings (comparing against everyone’s best scores over all time). The numbers in the Damage Done page of a report are something different. Those are performance: a comparison against all parses of your spec in the past two weeks. This tends to be a better metric than rankings for seeing how you’re really doing.