(FORTUNE Magazine) – What was really surprising about George Shaheen's sudden announcement last month that he was quitting the top job at the world's biggest consulting firm to go run an Internet startup that delivers groceries was that anyone was really surprised. Granted, the timing was awkward. In just a few weeks, Andersen Consulting will enter the testimony phase of its two-year-old divorce proceedings with Arthur Andersen; an arbitrator's ruling is expected early next year. For Shaheen, securing final independence for the breakaway consulting arm of Andersen Worldwide after building it into a $9 billion company over the past decade was to have been a "nice exclamation point to a wonderful career," says spokesman James Murphy. Had he stayed, in other words, Shaheen could have looked forward to a lusty round of applause from his 1,200 fellow partners at his retirement dinner. Instead, he gets 1.25 million shares of Webvan plus options for 15 million more. Shaheen can't talk, by the way; Webvan is in a quiet period, pending an October IPO. But as for why he made his move, here's a guess: He was seduced, simple as that.

In trading a secure seven-figure annual income for a chunk of dot.com equity, Shaheen becomes the third senior Andersen Consulting partner this year to have bolted under similar circumstances. Rudy Puryear, former head of Andersen's fast-growing e-commerce initiative, is now CEO of Lante, an Internet consultancy; Greg Owens, who ran Andersen's vital supply-chain practice, is the new CEO of software developer Manugistics. Further high-level defections are likely, predicts Owens, citing Andersen's stodgy partnership structure and the irresistible lure of "controlling your own destiny" by "being able to make a [public] company go."

All this comes at an especially delicate time for Andersen Consulting, just as the engine that drove its astonishing growth during the '90s--massive back-office information technology installations for the world's biggest companies--is slowing down. Andersen Consulting's growth rate for fiscal 1999, which ended Aug. 31, will likely be under 20% for the first time ever. Not to worry, Shaheen had been telling anyone who would listen. Andersen Consulting can sell e-commerce know-how to those same big companies, plus pick up new Internet clients further down-market where the really cool stuff is happening, and so preserve it's leadership role. A bedazzled business biweekly that isn't us even dubbed him the "Digital Messiah."

But now Shaheen is gone, and so is Puryear, the field leader most closely associated with the new direction. And suddenly Andersen Consulting is taking hits from a new breed of small-fry anxious to claim the e-commerce turf as their own. "I'll try to behave," says Robert Shaw, CEO of an Internet consultancy called USWeb/CKS, clearly relishing an opportunity to taunt the bully. "We rarely see them in the most exciting opportunities in the marketplace," Shaw says, adding that Andersen's call-in-the-troops-and-hunker-down service model "just doesn't resonate with the client base anymore." Robert Howe, CEO of Scient, says, "We think of ourselves as e-business marines, and they're this big, general-purpose army."

Albeit a formidable army, let's not lose sight of that. With more than a billion dollars in 1999 e-commerce billings, according to International Data Corp., Andersen Consulting dwarfs its Net-specialist competitors. "This is not a sinking ship at all," says IDC research manager Marianne Hedin.

What's happening at Andersen is symptomatic of a larger shift in consulting: away from back-office projects to improve operating efficiency (the legacy of Frederick Taylor and the principles of scientific management) and toward front-office efforts to transform customer relationships and increase market share. "Companies are starting to focus on how I grow my top line," says Jack Wilson, Andersen Consulting's managing partner for global markets. "Most everyone I talk to outside the firm believes that's going to be bigger than the back office ever was." And most everyone wants a piece of it.

--David Whitford