The flights are well over half-sold up front with 10 (or more) days to go, and you're looking on a peak business travel day. Simple supply and demand.. $720 C fares get snapped up so they'll see who will bite for full J. Worst case they'll try again at C levels a few days later. For 14-Nov (a Thursday), unsurprisingly it's the flights between 2pm and 9pm that are zeroed out in C.
And people wonder why there are no upgrades on SFO-ORD