A quick data-based thread on the possibility of a top-2 lockout for Dems in #CAGov. In the top-2 era (2012 on), there have been three midterms, featuring a total of 23 partisan statewide elections. The GOP's best-ever combined showing in a primary was 46%, in the 2014 controller's race.
Meanwhile, the *worst*-ever performance by a Dem who advanced to a general election with a Republican was 21.7%, which Betty Yee got in 2014 in that same controller's race. (Ironically, Yee also turned in the best primary showing ever just four years later.)
For a lockout, then, if the top #CAGov Dem turns in a Yee-in-2014-esque performance, Republicans would *still* have to take 43.5% of the combined primary vote—something they've managed once ever—AND split that pile of votes exactly evenly.
If the leading Dem does even a little better than Yee (and that was in a GOP wave year), then Republicans need an even bigger share of the vote. And if the two leading Republicans don't split the GOP vote equally, they also need a bigger share of the vote. If both happen ... you get the idea.
Of course a lockout is not impossible. But the odds are very much against it, and current polls are likely not a very helpful guide, given that the primary is three months away and most campaigns haven't ramped up their spending yet.