I thought so too. However, when he didn’t run, I thought for sure she would have picked him or Booker (who gave an Obama like speech at the convention). Either would have fueled minority and millennial turnout. I’m still baffled why she chose Kaine.
But even from a E. map perspective, there were better choices, e.g. Sherrod Brown, Bill Nelson, even Michel Bennet.
He was supposed to give her Virginia, making the path to 270 very difficult for Trump. OTOH, if she wins VA it will be in spite of Kaine, and if she doesn't, then she was dead in the water anyway.