Tell them to run the candidates that actually won in 2014 and not run the candidates that lost. Simple as that.
...Because telling Udall, Hagan, and Begich not to run again would have been good advice?
Obviously. Another candidate might have also lost, but they might have won too. Also without an incumbent in those 3 races they could have spent the money on another campaign. What is the point of running a candidate that you know will lose?
Begich ran a phenomenal campaign. If either Joe Miller or Mead Treadwell had won the primary, we'd likely be seeing a second term of him. There is literally no other Alaska Democrat that could've won it.
Udall could've been a surprise retirement that could've saved the Democrats. Even that hopeless buffoon Hickenlooper beat his challenger by a larger than expected margin.
I can't see a Democrat winning in North Carolina if Hagan didn't.