Weather reported by commercial weather routers appear conflicting and best as I could tell seemed to be moderate winds but enormous swells from a distant or dissipated storm. A guess I have as to the root cause is that the Captain maintained the planned, fastest course to Long Beach and took the 50ft swells on the beam causing radical rolls.
Container ships in particular are extremely pressured to maintain planned schedules. Missing a berth appointment can mean a week or three swinging at anchor and add millions of dollars to the ship owner's costs.
And never mind thousands of containers floating around for people to slam into.
As a container ship captain, I always took care of my ship, crew and cargo. I went around storms or slowed in heavy seas. I was never late. The other ship captain I alternated with never slowed down and was also never late. You could see the damage to the ship and cargo after he came through a storm.