Manchin is no Zell Miller, he is still to the left of even Collins and Murkowski. Corker and Flake may be bitter and petulant Never Trumpers, but they look like Genghis Khan compared to Joe. Ignore his reputation and look at how he votes. The only way he votes for confirmation is with Schumer's permission.
Corker and Flake may be hard core never Trumpers but they also know Kavanaugh is the kind of mainstream, top notch, reasonably conservative constitutionalist judge who would be at the top of their own lists if they were making the pick. They should be gratified that Trump picked him.