I doubt many people flipped to Trump just because of Kaine, but all the same, he absolutely bungled the VP debate.
I would certainly doubt that too. But the issue we are considering in this thread is not just how many voters (no particular ideology in our minds) might have switched to Trump because they didn't like either Clinton or Kaine. The issue is how many
liberal voters might have switched to Jill Stein or simply didn't vote at all because they were uninspired by the Democratic ticket. Stein got 31,000 votes in Wisconsin while Clinton lost to Trump by 22,300. Stein got 49,900 votes in Pennsylvania while Clinton lost to Trump by 44,300. And Stein got 51,400 votes in Michigan while Clinton lost to Trump by a mere 10,700. Just like in 2000, Ralph Nader was a liberal spoiler for Al Gore, Stein was a liberal spoiler for Hilary Clinton, and if the latter had chosen a running mate much more liberal than Kaine, then maybe that would have helped shore up the liberal base for the Democrats.