Lotus had 315 points in 2013 and just 10 points in 2014. That mus be the biggest fall of a F1 team. That's also because of the current amount of races and the current point system. But Lotus had a really struggling year.
So what about other examples in the past?
Ferrari: 1979: 113 points, 1980: 8 points
Williams:1997: 123 points, 1998: 38 points
What other examples of big falls from F1 team are there?