The people who know Romney well, and who alternately describe him as a barrel of laughs and a master persuader, can’t figure it out.

“I worry about him,” said Clayton Christensen, a fellow Mormon, an influential business theorist and a friend of Romney’s.

In his office at Harvard Business School, surrounded by certificates and the books he has written — including “The Innovator’s Solution,” “The Innovator’s Prescription” and “The Innovator’s Dilemma” — Christensen argued that Romney should open up more. He said the candidate should talk about the way he navigated acrimonious negotiations between the selling partners and the junior partners at Bain and Co. during a near-mutiny that nearly sank the firm.

“Oh my gosh, if you could tell that story in the context of a bifurcated Congress that can’t agree on anything,” Christensen said, adding that there were “hundreds and hundreds of people whose livelihoods depended on this. Why can’t he tell us this story? Nobody knows.”