Think back for a moment....The GOP gained the House in 2010....a mid-term elections. Then they finally gained the Senate in 2012, after several elections cycles when the TP screwed the GOP over. Again, it was a mid-term election. The GOP does well in mid-terms, but when there are national elections, and the voter turnout is substantial, they lose. So voter repression is the best GOP tool.
The GOP has a chance to shape an agenda and prove they can govern before 2016. If they do, they will have a chance in 2016 to regain the WH. If they don't they will lose bother the WH and the Senate. Simple as that!
Of course one could read those same results to mean that the Dems only gain lawmakers when they can ride a presidential victory but when made to fight man-man in the mid-terms, they lose.