They don't "force" people to fail, but the ranking does make it feel pretty intense. To be honest the failing cut off isn't very clear, and because our standard deviations are so tight I think they define failing in a more adaptable way than just by standard deviations, regardless of the "two standard deviations" by-line. But I've also never been worried about failing, so I haven't asked a lot about it. We're all ranked by percentiles, and the standard deviation is really tight, usually. A drop by 1 percentage point can be a lot bigger of a drop in percentile.