Bredesen wasn't even a bad candidate(Strickland and Bayh were), he was probably the best Democrats could have hoped for in Tennessee, it's just the state was too red and 2018 is too hyper-polarized for him to cut through.
I beg to differ a bit here; although Bredesen maintained a lead for many months, I always had a feeling that his Republican-lite campaign might turn out to be his Achilles' heel, and his support for Kavanaugh was probably the final nail in the coffin for a shellacking (remember that this move cost him a lot of potential support).