Re deceleration; DECEL light. Surely this only indicates that the system is engaged (and working), and presumably ‘without a gauged’ measure, the system does not indicate how much of the demanded deceleration is achieved? Furthermore, if such a quantitative system measured the decal, or more likely, the crew who normally has to judge the amount of achieved deceleration, it is difficult to differentiate between decal provided by the auto brake (brakes) and that from reverse.
Thus in this accident, reverse might have been providing the majority of the decal – poor runway friction, and when reverse was cancelled (habit) the brakes were not able to replace the demanded deceleration value, whether from auto or manual braking.
The position on the runway when reverse was cancelled (touchdown area for the other direction) may have be more susceptible to a wet slippery surface (rubber deposits), all of which add up to the crew having difficulty or insufficient time to detect the change in deceleration due to the lack of adequate braking; apart from running out of runway due to other contributing factors.