I'd say it's mostly due to a reduction in flying. We still are not flying as many hours as we did pre-COVID. The total number of passengers is still down, largely due to less international travel. Less passenger demand equals less flights scheduled, and the WOs get the leftovers after AA sends flying to the FFD partners. This means the company builds as many lines as they can but compared to pre-COVID there is not as much flying (not as many high-credit trips) left in the SAP open time pot after Round 1 lines are awarded.

That said, I think line values increased a lot for December. There were way more lines above 90 or 85 (or pick your reference point that's higher than min guarantee) hours compared to the last couple months.