From the article, it seems one of his former directors made that same claim, but supplied no numbers to back it up.

Preserved Jobs

Geoffrey Rehnert, a former managing director at Bain who worked for the firm until 1999, said that while Bain was focused on making money, its strategy was to create businesses that created jobs. Rehnert, who is now co-chief executive officer with Wolpow at Audax, said he’s “certain that Bain Capital was a net creator of jobs by a wide margin,” while he had no data to support that. At a minimum, Wolpow said, Bain helped preserve jobs that otherwise might have been lost.

Bain and the campaign didn’t respond to requests for job creation estimates.

A Bloomberg News review of several Bain deals during Romney’s tenure showed that workers in some firms had indications their jobs might be in jeopardy soon after Bain moved into management. In other cases, pink slips arrived after Bain and its investors had collected their profits and left debts behind.

Interviews with former employees and executives at Bain and companies it controlled, along with a review of Bain’s activities described in public documents and news accounts, paint a picture of an operation that wasn’t focused on expanding employment. Instead, Bain’s mission, like most private equity firms, was to generate gains for its investors.

Think Progress has more on Romney's record on job creation while he was Governor -- Romney Gives Obama A Failing Grade, But Massachusetts Ranked 47th In Job Growth While He Was Governor:

Former Massachusetts Gov. Mitt Romney (R) is focusing the early part of his presidential campaign on the economy, slamming Obama’s performance while touting himself as an experienced job creator. But while he assigns Obama a failing grade on his job performance thus far, reports from his time as governor show that Romney’s record as a job creator isn’t as strong as he would like voters to think.

Massachusetts, which Romney governed from 2003-2007, ranked 47th among the 50 states in job creation numbers during his tenure. [...]

What Romney leaves out of his stump speech, however, is just how bad his state’s job creation statistics were during his four years as governor. Different job creation studies rank Massachusetts in the bottom four states during Romney’s administration. A study by the independent think tank MassINC ranked the state 49th in job creation from 2001-2007, ahead of only Michigan. And according to the U.S. Department of Labor, Massachusetts ranked 47th, ahead of only Michigan, Ohio, and Louisiana. Michigan and Ohio, both located in the Rust Belt, faced heavy job losses due to the flight of manufacturing jobs from the Midwest. Louisiana, meanwhile, lost hundreds of thousands of jobs in the aftermath of Hurricane Katrina in 2005.

During Romney’s period as governor, Massachusetts’ job growth was just 0.9 percent, well behind other high-wage, high-skill economies in New York (2.7), California (4.7), and North Carolina (7.6). The national average, meanwhile, was better than 5 percent.