ABC News' Amy Walter reports: The President and lots of commentators have been obsessing about the so-called enthusiasm gap and its impact on this election. In recent days there’s been some polling – most notably from NBC/WSJ – that shows Democrats starting to close that gap. When asked who they’d be more likely to support in Nov., voters gave Republicans a 3-pt advantage. A month ago Republicans had a 9-pt advantage on that question. We’ve also seen some Democratic candidates poll better in traditionally blue states like California, Washington and Maryland. That said, this tightening of the generic ballot does not mean that Democrats are out of the woods or that Republicans are less likely to gain control of the House. Here are some important things to keep in mind. First, the generic ballot is an important indicator of overall party strength and enthusiasm but it reflects the national environment and understates the local dynamics. Democrats are already overexposed in districts that lean Republican. So the bigger the generic ballot gap, the wider the playing field becomes and districts that are currently rated as “safe” for Democrats become more competitive. In other words, we go from talking about the possibility of a 40-50 seat pick up for Republicans to the possibility of a 50+ seat night for the GOP. Second, while Democrats have been releasing plenty of CD-level polling to try and show that their candidates are alive and kicking, it’s important to point out that in almost all cases, the Democratic incumbent was under 50 percent. That’s a terrible place for a sitting incumbent to be a month out of an election. Undecided voters tend to break disproportionately for the challenger. Finally, “wave elections” are really misnamed. We should think of them more like tornados. There are some places where the winds will level everything in its path. But, there will inevitably be those candidates who survive, even while all the houses surrounding him/her have been reduced to rubble.