[crazytony]

Looking at flightradar24, the only real upset I see is the turn over the southern Sierra Nevada range which is also ~55 minutes before arrival into OAK.

Wonder if mountain waves play any part in this incident? It's the only thing I can think of that could possibly generate a dutch roll without continuing flight stability issues. (They could have also turned on/off something like the yaw damper in the cockpit but that's not specifically called out int he report)

I can't imagine the standby PCU causing this incident unless there was some kind of electrical or pneumatic issue causing it to engage.

But 737 + PCU issues (yes, I know it's been redesigned) is never a good day.

Hopefully we'll get a NTSB report on this one.