Lol
Bush. Dole. McCain, Romney were all moderate and liberal, by your measure they should win handily.
Well, Bush won. In fact, George W. Bush won twice.
The others cited all lost--albeit as far back as 1996, in the case of Bob Dole.
But please note that these were all presidential nominees. It is nominees for the Senate that is a matter of significance in 2014. And nominees for the Senate that cannot attract votes from beyond their own base are not likely to win in the general election.
Why do you suppose that Harry Reid is now the Majority Leader, and Mitch McConnell is the Minority Leader, instead of the other way around?
Senators generally make poor Presidential candidates.
If it were the other way around nothing would change