Jan 11, 2011 09:06 GMT  ·  By

The head of one of Microsoft’s three $15 billion businesses has announced that he is leaving the company.

Microsoft Chief Executive Officer Steve Ballmer sent an email to all employees on January 10th, 2010, revealing transition plans for Bob Muglia, the President of Server and Tools Business.

Ballmer underlines that with STB in a position of strength, now it’s the best time to think about change.

It appears that Microsoft’s CEO and Bob Muglia have been discussing the future of STB as well as the necessity to accelerate growth. Part of the solution, at least as far as Ballmer is concerned, is to put new leadership in place for STB.

“This is simply recognition that all businesses go through cycles and need new and different talent to manage through those cycles. Bob has been a phenomenal partner throughout this process, and he and his leadership team have the right strategy in place,” Ballmer stated.

“In conjunction with this leadership change, Bob has decided to leave Microsoft this summer. He will continue to actively run STB as I conduct an internal and external search for the new leader. Bob will onboard the new leader and will also complete additional projects for me.”

Muglia also sent an email to STB employees on January 10th, 2011, which Mary-Jo Foley shared with the world. The message confirmed his imminent departure from the software giant, with the former STB President revealing that he will be moving on to new opportunities outside of Microsoft.

This move comes after Muglia dedicated no less than 23 years to the Redmond company.

Muglia called Microsoft a blessing, and praised the work done by his team, and the collaboration with customers and partners, as well as revealed excitement about the foray into Cloud computing.

However, he also talked about integrity and leadership, and there are already speculations that Muglia was somewhat forced out of Microsoft because he failed to agree with the path that Ballmer has set for STB.

“As a leader at Microsoft, I have a responsibility for delivering results to our shareholders. STB has performed well – with revenue growing from $9.7B in 2006 before I took over, to $14.9B reported last July, and operating income climbing from $3B to $5.5B over the same period.

“That’s over a 50% increase in revenue with a near doubling in income. That growth continued during the first quarter of our FY11. There are few organizations in the industry who have demonstrated the same results,” Muglia stated.