If deep red Tennessee flips 13% wouldn't that suggest

[EdmondDantes_]

3. It's hard to make a direct comparison due to being a special election

And not on a normal cycle, but yes it's a good sign.

It's hard to really say if other areas might have shifted more though because there's only a subset of people who are able to be shifted. For example if a district is 75% Democratic, I think it would be harder to get to 90% just because some people won't switch parties, or will think that they could vote Green party or something to try to shift the local Overton window as compared to a district that was 60% Republican going to 51% Democratic.