Oil is down - why isn't diesel a lot cheaper? Port problems

Oil is down substantially yet diesel hasn’t declined nearly as much because refiners are making more money.  Over the past year, refiners have averaged $10/barrel for processing – the so called "crack spread”.  Now the crack spread is running around $25/barrel.  
Meishan terminal at China's Ningbo port, the third largest port in the world, closed for 2 weeks because of a single COVID case.