His praise of Obama as a man who is "cool on the outside but burns for America on the inside" was watched from the wings by Obama, who then joined him on the Time Warner Cable Arena stage, where the incumbent will speak on Thursday.
In turning to Clinton, Democratic strategists hoped to rekindle fond memories of that last Democratic president's second term, when unemployment touched record lows, the stock market doubled in value and the budget was even balanced for a couple of years. Clinton's message was that Obama hasn't delivered that kind of return because he was dealt such a bad hand.
His speech was greeted with laughter from delegates - and an eye roll from Michelle Obama when he praised her husband's "good sense" in marrying her.
Those Democratic planners must have also been looking to Clinton's address to erase more recent memories of an afternoon that was as dismal for the party as the soggy Piedmont skies.
It started with the announcement that Obama's acceptance speech Thursday would be moved indoors from the spacious Bank of America Stadium - a move that was blamed on a chance of thunderstorms but prompted cackles from Republicans that the real reason was fear of empty seats.
It got worse when a decision that reportedly came down from the president himself - to kowtow to fearmongering headlines on right-wing sites like the Drudge Report and insert the words "God" and "Jerusalem" into the platform - caused anger, confusion and, of course, even worse headlines.
Apparently, Tuesday's advice from Massachusetts Gov. Deval Patrick - who got a standing ovation when he told delegates "it is time for Democrats to grow a backbone and stand up for what we believe" - went in one ear and out the other.
It fell to "The Big Dog" to clean up a big mess.
Four years ago, nobody could have predicted that the great white whale of Democratic politics would have stolen center stage at the confab to renominate Obama. After all, it was the upstart, then-first-term senator from Illinois who in 2008 denied Bill Clinton a return to the White House as the First Spouse after a primary spat that really healed only after Obama tapped Hillary as his secretary of state.
Since then, the 42nd and 44th presidents bonded a bit, and it's likely that Clinton sees a successful second Obama term as validating his own political legacy and making it more likely that his wife could win in 2016, if she ran. But Obama was the one who needed Clinton more Wednesday night, to place his presidency in a broad historical context.
"Clinton can probably sell Obama better than Obama can," said Larry Sabato, the University of Virginia historian and presidential pundit. He explained that it was easier for the ex-president to blame lingering high unemployment on the economic disaster Obama inherited from George W. Bush. "Clinton can say that without it sounding like a whine."
Costas Panagopoulos, director of the Center for Electoral Politics and Democracy at Fordham University, said that Clinton's strong point is that he once had an uneasy relationship with Obama, but "he's come around and become an ally and a proponent of the president - convinced by his deeds and his actions."
But there was one final big irony in Clinton's appearance. One part of his mission - reaching out to to white, blue-collar swing voters - was supposed to be the job of Vice President Joe Biden. But unlike the Republicans did with Mitt Romney's running mate Paul Ryan, the sometime foot-in-mouthed vice president was apparently not ready for prime time Wednesday, not when the Democrats' great communicator was bookable.
Contact Will Bunch at bunchw@ phillynews.com or 215-854-2957. Follow him on Twitter @Will_Bunch. Read his blog at Attytood.com.