My blog posts have a reasonably unique writing style. When I asked opus to work out who wrote an unpublished paragraph, all it did was select the decent insults and search the web for them.

After that it gave up and said it didn't know.

So either, Kelsey writes in such a unique style that its really obvious, or they repeat themselves with goto phrases that give them away.

When I tried to re-produce the test, it found Kelsey's blog about the test. So dunno, maybe it did it? but I can repro.