I actually don't think midterm primaries (at all levels) generally have any broader meaning. Political reporters are always trying to seize on A Narrative by picking a few races, when idiosyncratic local issues (including particular candidates) are often a bigger explanation.
If there's a story here it's the amount of money thrown at lefty challengers, which is a story whoever won any particular race. Maybe that the money didn't always work is a story! Maybe not!
