The new Difficulty score gets pretty aggressively scaled, because we found that the distribution of PA/DA was bunching up a bit, and fell almost entirely in the 25-85 range (looking across an entire SERP). So, a 25 gets scaled down to nearly zero, to give the new metric more granularity.
It looks like the CTR-adjusted PA for "Naturmode" on Google.de (for example) is right around 26, so it may be that the PAs have gone down a bit over time as well. Even by the non-weighted metric, I'd expect that to be a solid 10 points lower than the old difficulty score.
We're going to dig in and try to find out if the rescaling is too aggressive, once we have more data from real-world KWE usage. In general, though, you're going to see a bigger range of difficulty scores with the new metric. It's pretty tough to meaningfully compare the old and new scores.
