Candidates who SHOULDN'T try again:
Stewart Mills (MN-08)
Joe Garcia (FL-26)
Randy Perkins (FL-18)
Paul Babeau (AZ-01)
Matt Heinz (AZ-02)
Monica Vernon (IA-01)
Emilio Huerta (CA-21)
Danny Tarkanian (NV-03)
What's wrong with Matt Heinz (AZ-02)? He made it close.
AZ-02 2014
Martha Mcsally: 50.0%
Ron Barber: 49.9%
AZ-02 2016
Martha Mcsally: 56.7%
Matt Heinz: 43.3%
Matt Heinz is a bad fit for the district unfortunately. He got blown out. He should return to the state legislature. Maybe he could run for Grijalva's seat when he retires...
At the same time you are comparing two different campaigns. McSally ran as an incumbent this time round. She was going to have a bounce due to that.