Yes but don't call that a cliff - because what people called the cliff in 2011 and early 2012 Pirellis were that the laptime would suddenly disappear. Raikkonen China?
4 seconds per lap is not a cliff???? So again lets not get lost in definitions.
My point is basically the same as Gary's that Ferrari had plenty of data to make an informed decision and not gamble. They ignored the data or didn't analayse it enough and were over confident with Alonso. Still they have different opportunities to react.
1. Pit Alonso right after HAM to cover him and capitlize on their small pit stop mistake.
2. Pit ALO two or three laps after HAM pit stop when HAM started gaining on Alonso and Vettel.
3. As Gary says 10 laps before the end they had enough data to react and pit. They would have passed Grojean on fresh tires.
4. Pit when Vettel did to cover for him.
There is no reaction at all at least in four occasions I am pointing out. They just waited lap after lap until ALO was losing 4 seconds per lap to Vettel and finished 0.4 sec to Rosberg. Extremely risky the inability to react by the pit wall.