In that situation, all the Dems had to do was not be crazy: Don't have a hundred new, expansive proposals. Acknowledge that you have to work with the GOP-led House, so there are going to be limits on what you can do. The Dems were able to avoid crazy, so they won.
In 2016, the Dems might be running against sane opponents, so it's going to be much harder for them. The sane crop of candidates in 2014 didn't push the idea that all pregnancies are sacred (so no abortion even in the case of rape or severe deformity) They didn't say the government should be shut down if we don't get our repeal of Obamacare. Actually, I assume they didn't do this. I didn't see their TV commercials. But I didn't see over-the-top commercials critiqued or lampooned either.
So if the 2016 GOP candidates aren't going to be crazy, how will the Dems win? That's a question they should be asking themselves. If the Dems don't want to lose in 2016 the way they just lost, they will have to come up with a damn good answer to that question. I'll be looking for how that shapes up.
It was easy to beat this bunch.