I was just looking at the moderator history page on RPG, and noticed that one of the moderator's stats are red? Is that because they haven't done anything recently, or is there some other meaning to the coloration?
Mods that have not been around for a week are "hot", a month are "supernova"
Mods that have 10% or less in a stat from the stat leader (in monthly view only for stats with a higher max than 30) are "hot". Mods that have 2.5% or less are "supernova"
The moderator with the least amount of activity for the column gets the privilege of having it bolded and colored red. The column for the moderator with the second least amount of activity is colored orange.
To paraphrase some of the discussion in Teachers' Lounge, it's to give some indication to the person with the least amount of activity that they might want to take on more of the routine moderator work, and as an indication to all moderators and SE staff what the effects of one of the moderators taking some time off might do.
That is, if one of the least active moderators takes some time off, it's not a big deal. But if there are only red or orange highlighted moderators left, the site could use another moderator.
All that said, the coloring seems to be a bit naive: if you happen to be in last place, you get the red badge of shame even if you're only one point (one comment, one closure, one vote) lower than the next moderator. And if you all happen to be tied (like at the start of the new day where everyone's totals are zero), everyone gets the red!