Look at the similarities of the early debates:
1st Debate, 2012: Obama was very close to having the race completely locked up, perhaps even getting his 2008 margin all over again. The debate happens, he loses by a wide margin, and Romney gets a significant bounce.
Donald Trump never had the race nearly won. It was close to a tie. Trump did horribly. Subsequent polls suggest a collapse.
I doubt that Kaine or Pence did anything to lose core support -- or convince anyone who did not already lean toward Clinton or Trump. Pence was more ideological (as on abortion) and more willing to push special interests (coal). We shall see as the polling continues.
Pence is not as poor a VP pick as Ryan. Ryan had a House seat to defend while running for the VP spot, and he hedged.
I see evidence of a collapse for Trump in polls of Pennsylvania, Florida, Virginia, North Carolina, and Florida. If you are to compare Donald Trump in 2016 to Barack Obama in 2012... Barack Obama said nothing offensive, and Donald Trump said much that could offend many of us. Trump furthermore got caught in some lies that he cannot undo.
The VP does not count that much. Think of 1988: Senator Lloyd Bentsen made the rhetorical equivalent of a punching bag out of Dan Quayle, and the elder Bush won in a landslide.
Barack Obama is a cautious, gracious, erudite speaker generally good at avoiding offense to people. Donald Trump is the near opposite in those aspects of political debate.
What has The Donald ever said that convinces you that he can win convincingly in a debate? "Sympathy swing"? Not for the Presidency. One might show sympathy for a relative who has done some backsliding (like going off the wagon) who shows some repentance, but that sympathy is not enough to advise him to go into elective politics.
I can see an analogy between Barack Obama and Ronald Reagan with Hillary Clinton as the equivalent of George H W Bush. But Tim Kaine is definitely not the new Dan Quayle. Comparing Donald Trump to Mike Dukakis is a travesty; Dukakis had some political virtues.
Hillary Clinton wins, Democrats take back the Senate, and the House becomes a haven for reactionary obstructionists. We have seen that as the norm between 2011 and 2016.
What merits the worry?
