Juniper Networks said today that Kevin Johnson will become its CEO and leave Microsoft as head of its online operations. Juniper said Scott Kriens, chairman and CEO since the company's inception 12 years ago, will continue as chairman and remain active in company strategy and leadership development.

Johnson was tapped to lead Juniper through its growth stage beyond $3 billion. His background in engineering and experience in scaling and leading companies through rapid growth were attributes sought by Juniper, according to Kriens and CTO and founder Pradeep Sindhu.

News of Johnson's departure from Microsoft comes just a week after the company released financial earnings dragged down by its online services group. Microsoft will split up the group he ran.

Microsoft plans to divide its Platforms and Services division, the group Johnson led, into the Windows/Windows Live group and an Online Services group. Both organizations will report directly to CEO Steve Ballmer.

Senior vice presidents Steven Sinofsky, Jon DeVaan and Bill Veghte will lead the Windows group, reporting directly to Ballmer. Microsoft plans to create a new position to run the Online Services group and will look internally and externally to fill that job, the company said. Satya Nadella will continue to run search, MSN and ad platform engineering efforts, and Brian McAndrews will continue to lead the Advertiser and Publisher Solutions group within the Online Services group.

Johnson has been with Microsoft since 1992. "In some ways, he has had a career trajectory somewhat like Steve Ballmer's own. He was definitely on the short list of people who would be a potential CEO replacement," said Rob Helm, an analyst with Directions on Microsoft.

Yet, he was in a difficult position as head of the online group. “In the end he was responsible for the online strategy, which is by far the weakest part of Microsoft’s business,” Helm said. Johnson hasn’t managed to improve market share or revenue shortfalls through organic growth or acquisition, Helm noted. “And spending on that business has been tremendous enough to weigh on the company’s results. I don’t know if he jumped or was pushed, but there’s no question he had a difficult job and he may not be the last manager to fall on this particular sword.”

The IDG News Service is a Network World affiliate.