Watching the video footage, Graham noticed another correlation: the longer he took to decide a group’s fate, the less likely the group was to succeed. “When you have to talk yourself into something, it’s a bad sign — that’s true also of relationships, hiring and so many other parts of life.” (Graham has a rhetorical talent for moving swiftly from the valley to the universal.) But after ranking every Y.C. company by its valuation, Graham discovered a more significant correlation. “You have to go far down the list to find a C.E.O. with a strong foreign accent,” Graham told me. “Alarmingly far down — like 100th place.” I asked him to clarify. “You can sound like you’re from Russia,” he said, in the voice of an evil Soviet henchman. “It’s just fine, as long as everyone can understand you.”

This was bad news for Strikingly’s David Chen, who moved in 2005 from Guangzhou to the United States to attend high school at Houghton Academy, in upstate New York. He spoke English fluently but struggled to pronounce words like “build,” “mobile” and, most ominously, “strikingly.” Yet Chen had clearly established himself as the fledgling company’s impresario and spokesman. While his partners spent their days writing code and fixing software bugs, Chen met with lawyers, potential investors and reporters. In a Forbes magazine article, a college classmate wrote of Chen’s evolution since moving to the Bay Area: “He used to tell me, ‘I want to build a product that helps social entrepreneurs and changes the world.’ Now he tells me, ‘I want to be the next Airbnb or Dropbox.’ ”

One week before Demo Day, Graham told the Strikingly founders that Chen’s accent was too strong. The quiet, reserved Bao — who spoke less frequently than either of his partners despite being the group’s only native English speaker — would have to deliver the pitch instead. Bao denied that he was anxious, but as he tried to memorize the pitch, he grew even quieter than usual. “I haven’t gotten to the point where I’m comfortable with public speaking,” he admitted. There was only one day before Rehearsal Day, when every start-up would deliver its pitch in front of the entire Y.C. class. One Y.C. partner thought it odd that in Strikingly’s final pitch meeting, Chen still did all the talking while Bao sat mutely off to one side.

Michelle Crosby, meanwhile, pacing around the rental condo that served as Wevorce’s office, hadn’t even begun to practice for Demo Day. But she had been perfecting her pitch for years. When she was 3 years old, her parents had, as she put it, “one of those ‘War of the Roses’ divorces.” At 9, she was called to the witness stand, where a lawyer asked her, “If you had to be stranded on a desert island with one parent, which one would you choose?” She couldn’t answer the question. “I knew then that the system was broken,” she told me. Her story, far more emotionally wrought than those of her Y.C. competitors, has become one of Wevorce’s most valuable assets. Unmentioned in the pitch is the fact that Crosby herself, after a 12-year marriage, divorced — amicably, she says. One source of tension in her relationship, she said, was her determination to start Wevorce.

On the cusp of becoming a partner at her corporate law firm, Crosby had what she calls “a quarter-life breakdown” and quit. She attended Harvard’s mediation training program and developed a six-step process designed to yield an amicable divorce. Using a software program with a video-game-like interface, the couple, with the help of a Wevorce mediator, creates an exhaustive divorce contract, its stipulations extending to such subjects as a child’s diet and curfew. Crosby puts the average divorce at around $27,000 in legal fees; Wevorce charges a flat rate of $7,500. She imagines a Wevorce office for every 400,000 Americans and estimates $1 billion in annual revenue. “We want,” she said, reaching for one of the valley’s most ubiquitous buzzwords, “to disrupt divorce.”

Crosby’s business partner is Jeff Reynolds, 38, a kind, jittery software designer. He had found it difficult to explain to his wife, a dental hygienist in Boise, and their two children, 9 and 12, why he moved to California for at least three months to start a divorce company. Crosby can sympathize — her current boyfriend of a year, a homebuilder in Boise, has grown frustrated by her absences. “It’s one of the gifts of Y.C. that you get three months of ‘Sorry, don’t bother me, I’m building something,’ ” Crosby said. “But you can’t sustain this. Everything else would start to crumble.”

When Crosby and Reynolds joined Y Combinator, Wevorce had a single office in Boise. Graham told Crosby that investors would be impressed if they were to expand quickly to other cities. In the next two months, they opened offices in four states. Each required a lawyer, a counselor and a financial professional, and they had to be trained. In the previous weeks, Crosby flew between Seattle, Portland, Boise, San Francisco and Asheville, N.C. The term of art for this is “nefarious business” — creating the appearance of success in order to attract actual success. Fake it till you make it. But Wevorce’s success rate wasn’t fake: only one out of 110 Wevorces has gone to court.