Hard to say what's going on there.
I would not trust any polls that were conducted over the last days.
It will take another 1 or 2 weeks until there's a clearer picture again.
Also remember that SurveyMonkey/Axis poll that had Blackburn up 14 points a few months ago and then all the other polls showed Bredesen with a lead ?
I pretty much agree with this.
Polls are obviously messed up right now due to the Kavanaugh news cycle - Republicans are more enthusiastic right now than they will be in a month, when Kavanaugh will be a distant memory and healthcare will likely dominate the headlines. There's no reason to take any one poll as gospel at any time, but especially not one taken right now.