[The] highly successful "mixed" lawprof bloggers all blog from, and to a readership primarily on, the political right....Obvious and inflammatory theory #1: Lefties are more easily confused.
The couple of genuinely "mixed" lawprof bloggers to the left of center – I'm thinking, I guess, mostly of myself and Michael Froomkin, and I'd probably throw in Ann Bartow of Feminist Law Profs as well -- don't hold a candle to their readership or their influence.
What do I make of that? To be honest, I don't really know. I certainly don't think the legal academy is skewed towards a Republican/conservative viewpoint; it isn't.
The preeminence of right-of-center "mixed" lawprof bloggers may, however, reflect an overall blogospheric tilt to the right; look at the TTLB ecosystem's ten "Higher Beings" and you'll see that seven are blogs from the right, whereas only two are blogs from the left.
Or maybe it reflects something else entirely. I'd be curious to know what you think.
In any case, Larry[ Solum's] thesis – that lawprof bloggers who blog about law as well as lots of other stuff will confuse their readership and drive them away, and that their blogs will therefore fade away – appears to be incorrect, or at least incomplete. Something surely explains why certain "mixed" lawprof blogs are among the most successful blogs in the blogosphere, even among lawprofs and other consumers of legal scholarship, and something surely explains why right-of-center ones do a whole lot better than left-of-center ones.
Obvious and inflammatory theory #2: The flexible, wide-ranging intellect leans right.
Anyway... I think readers like mixed topic blogs more. Remember when Stephen Bainbridge took a vote about whether to put his material about corporate law on a separate blog? The readers strongly rejected the idea.