Lawrence Lessig has an op-ed saying
something somewhat similar to what I said about O'Rourke. Like me, he thinks that O'Rourke's uncompromisingly left-wing positions probably cost him the chance to unseat Cruz. For Lessig, the lesson is that Democrats should campaign on a centrist anti-corruption message, using Billie Sutton's South Dakota gubernatorial campaign.
On one hand, I think that there is something to this, given that Trump has run the most brazenly corrupt administration since at least Harding. But on the other hand, the Democratic Party is the party I think most Americans associate more with corruption (or is it just me, coming as I do from Massachusetts?) and the party which just re-elected Bob Menendez, which makes this a very hard sell. But on the third hand (everyone has three, right?) one-party rule always tends to lead to corruption to some extent. I know the Texas and West Virginia branches of the GOP are wicked corrupt, so it's definitely a good message on local issues in red states.
I'm also not sure that Democrats need to move to the center on all issues. It probably helps to have some issues to fire up the base, but I think that candidates should carefully consider which issues are so important to them that they are worth risking losing over. I think standing up for BLM was worthwhile, and a lot of Texas Democrats probably think pushing for single payer is. But when you advocate something which has no chance of passing, as is the case with banning AR-15s and impeaching Trump, you are riling up people who disagree with you for no reason. And saying you are open to abolishing ICE when you really mean you'd like to reorganize Homeland Security? That is terrible messaging.
It's also worth noting that while I think the article is interesting, South Dakota is a highly elastic state (moreso than Texas)
and people are more prone to voting for opposite-party governors in deep red/blue states than they are for federal office or even state legislature, so Lessig's argument that "Sutton did better in South Dakota for governor than O'Rourke did for Senator in Texas" isn't really persuasive as a single data point.