Parrabellum, the 737-800 MTOW is approx 79 tonne, carries 20.8 tonne of fuel and ML - DPS is still a long way in the 73, especially if there is weather at the other end or the ALT add to that headwinds coming into winter. Like someone else posted, they needed the fuel at the other end. Pencil thickness wouldn't have come into it either, dont use those charts for TOW calculations.