Nate Silver does the math in explaining a 31 point swing against the Dems in one year in one state:
The final score: national environment 13, Coakley 14, special circumstances 4.
If you follow through on the math, this would suggest that Coakley would have won by about 8 points, rather than losing by 5, had the national environment not deteriorated so significantly for Democrats. It suggests that the Democrats would have won by 9 points, rather than losing by 5, had the candidate been someone other than Coakley. And it suggests that the race would have been a 1-point loss (that is, basically too close to call), rather than a 5-point loss, even if Coakley had run such a bad campaign and even if the national environment had deteriorated as much as it has, but had there not been the unusual circumstances associated with this particular election.
A perfect storm of specific and broader factors that killed the prospect of substantive reform on any major issue in this country for a very long time.