This is what Democrats did wrong and Republicans did right.
This. This was a boring election. The Democrats had no rallying cause (like in 2006 and 2008) or charismatic and inspiring leader (like in 2008 and 2012.) The election was uninteresting and Democrats, especially young ones had nothing to fight for. They didn't show up. The Republicans only cause was really blind Obama hatred, but for them that's enough.
The not all that well attended DFL party I was at last night is kind of a microcosm of that, in addition to being far less attended than anyone I've ever been to (including 2010), it was also much less disproportionately young.