Photo: Win McNamee/Getty Images

In evaluating tonight’s vice-presidential-candidate debate in Virginia, it is important to remember these undercard events don’t change many votes. If they did, President Michael Dukakis would have been running for reelection in 1992 and there’s no telling if another Bush or either Clinton would have ever won a nomination.

Knowing this, both veep prospects arrived in Farmville with objectives other than “winning” this debate. Kaine had the easier job: reinforcing talking points about Donald Trump that the Clinton campaign thought were effective in the first presidential debate and in the contest generally. Pence’s task was more complex: He needed to stop the negative news cycles his campaign had endured since the Hofstra debate; provide the most reasonable defense of his running mate he could muster; make more coherent criticisms of Clinton than Trump was able to do; and in general reassure both Republicans and independents that the GOP ticket was the obvious choice for people who wanted change in a respectable conservative direction.

Pence succeeded conspicuously at his more complex task, while Kaine succeeded at the expense of both style points (he was the chief interrupter tonight) and opportunity costs. The latter, compounded by the constrained line of questions moderator Elaine Quijano pursued, were substantial. A whole host of glaring policy differences between Trump and Pence were left unexamined, including the Iraq war, criminal-justice reform, and trade (a topic that did not, astonishingly, even come up). Pence’s shaky record in Indiana — especially the poor handling of “religious liberty” legislation that made him look like a bad bet for reelection before Trump took him off the Hoosier GOP’s hands — was not mentioned, either. And most important, Kaine too often let his opponent get away with finessing, ignoring, or just plain lying about Trump’s record or positions.

Fact-checkers and the chattering classes will do some of the things Kaine failed to do in Farmville; Donald Trump is not a standard-brand conservative or conventional Republican, no matter how Pence was allowed to describe him in this debate. But beyond that, Kaine repeatedly and exhaustively and redundantly brought up Trump’s failure to reveal his tax returns and/or pay income taxes; his insults to women and minorities; and his recklessness on all things nuclear. You have to assume the Clinton campaign has decided these are critical issues for their targeted voters — presumably millennials, unenthusiastic Democrats, and some moderate Republicans — to internalize.

If they are right, then it won’t matter that Kaine lost this debate on points or that he did less for his own political career than Pence, whose alleged presidential ambitions may now rise rapidly (the biggest losers in Farmville may have been putative 2020 candidates Paul Ryan, Marco Rubio, and Ted Cruz).

There’s even a possibility Pence’s performance could have the nasty aftertaste of making The Boss look bad by comparison in his next debate. But for now he’s done his job, and perhaps Kaine did as well. Pence helped change “the narrative” for the race, but it’s doubtful he did anything to cut into Clinton’s lead.