Sherlock keeps a blog/diary too - proving that Anderson is responsible for pretty much every major unsolved case ever. Whenever Sherlock gets annoyed at Anderson he comes home and writes a rant PROVING Anderson killed Archduke Ferdinand or JFK or whatever. And because Sherlock is brilliant, he's come up with some pretty convincing arguments framing Anderson (if you ignore the minor fact that Anderson wasn't actually alive for most of them).

Maybe he's annoyed that his blog doesn't get as much traffic as John's does? Or maybe Lestrade and the other Yarders find out about it?