Do Dashboard Trending Graphs account for deleted devices?

Hi, just looking for a little clarity on how the graphs work in the dashboard.

I have deleted devices before where there is a huge risk score (300k+) and expect to see a huge reduction in the trending, but I never seem to see that. I suspect that what might be happening is that the entire trend line is reduced, as if the device never existed.

Can anyone from R7 confirm or any users share their experiences with this?