Over extensions when using Auto pose?

Over Extension

I've noticed that limbs tend to over extend a bit between keys when using the Auto Posing tool and there doesn't seem to be a way to fix it without setting the interpolation to Linear or Stepped. All of the bezier modes don't fix it. Normally this is something I'd fix in the curve editor, but I can't do anything with tangents, I can only move the points which wrecks the animation.

I've never seen a tangent look like this before ^