In the 3+ years of Jerry Brown's third term as governor he's been fairly centrist on budget issues. This has been a surprise to Republicans and is the reason he has inordinately high approvals from California Republicans. Brown unveiled a revised budget and this one is fairly frugal with higher than expected revenues. Brown's election strategy appears to be one that he's above politics and party and for doing what's right for California. This is likely going to get him centrist Republican and NPP votes and might result in him breaking the Democratic ceiling by a few points.
The downside is that progressives are unhappy with Jerry. It's possible that some progressives won't go to the polls, as a way of protesting Jerry. They may surmise that he doesn't need their votes to win, so they don't need to go. In fact, his "adult in the room" strategy may result in him gaining more centrist votes than his progressive losses. The problem with that is the progressive who stays home would've voted Democratic for congress, the state senate, and assembly. The centrist NPP and Republican who votes Brown is far more likely to split their ticket and vote for the same people they always do, Republicans down ballot. They aren't changing their assembly vote just because they like Jerry. So while Jerry's strategy may end up giving him an unprecedented percentage of the gubernatorial it could mean Democrats losing some close races down ticket.