2004 and 2016 were the worst for the Dems. Losing to Trump and Dubya.
Because Kerry was swift boated and Clinton was sabatoged by Wikileaks. All techniques used by GOP to depressed turnout to key constituencies.
And, it was especially depressing, because those voter suppression techniques worked. Unlike in 2008 and 2012, there were no voter suppression used and turnout was at an all time high and Obama won.
Clinton got the same amount of votes as Obama, but in WI, PA and MI, the margin of difference votes went to Johnson/Stein that would have went to Sanders or Biden.
I wouldn't say Wikileaks sabotaged Hillary, they exposed the Bush administration and Assange is pretty liberal. IIRC he supported Sanders, but I'm not sure about that.