I guess this is my fault to some extent, since I'm apparently the most prolific moderator. Denny and I are the only two of the four mods to have done any moderating at all this quarter, though.
Basically, I don't want to be a total ass when I close a question, and want to have a good, solid reason behind it. Sometimes I'll get the feeling that it's not a good question, but I don't have the time to spend looking for the similar question that applies, or the time to coach the person asking into the kind of useful question that you're looking for. So I wind up just letting it lie, or just doing a quick edit to fix the painful grammar problems.
I also don't particularly want to run new people off.
I'm pretty much just trying to keep ahead of the worst stuff, but haven't had as much focus on the overall strategy of keeping the site reigned in to the original goals.