– Dean Lester had been away from Microsoft for more than six years when the calls from former colleagues started rolling in at the end of 2016. He had just finished establishing a Redmond engineering center for Qualcomm and was considering his next move.

“Hey, you should think about coming back,” the messages said, sent from peers he met during his 13-year stint at Microsoft.

When Lester, an engineering director, left the company at the end of 2009, he was craving some time off and new challenges, but he was also feeling frustrated with the way Microsoft teams were being run — they were so focused on rapid project launches that people were burning out.

That was changing, the chorus of former co-workers told him. He should take another look.

He did, and after many vetting conversations, took a job as a partner director of engineering in January 2017, overseeing groups developing mixed reality and HoloLens technology. That made him one of the more than 2,200 employees who have rejoined Microsoft since CEO Satya Nadella took the reins in 2014.

Microsoft has always had “boomerang” employees, as have other tech companies in the highly competitive industry. During the few years before Nadella stepped into the role, about 12 percent of the company’s new hires in the U.S. each year had previous job stints at the company. But that number ticked up to 16 percent, or 621 boomerangs, between July 2014 and July 2015, starting a few months after Nadella took over as CEO.

For the recent Microsoft boomerangs, returning to Redmond feels like stepping into a company that has changed — albeit one where that still occurs slowly.

Nadella — in public speeches, in his book released last year, in posters hanging on break-room walls within the company — is emphasizing the idea of “One Microsoft,” or a collaborative environment that hasn’t existed in many parts of the company in the past.

Under co-founder and first CEO Bill Gates, and even more under his successor Steve Ballmer, Microsoft had become known as a company mired in internal competition among managers, teams and employees. It also pitted employees against each other in annual reviews, a system, since changed, that had faced widespread criticism from employees.

This internal competition, some believe, diverted Microsoft’s attention away from competing against Apple, Google and other rising giants of the 2000s.

Nadella’s approach has fewer pointy edges. Teams should work together and build on each other’s work, he proselytizes, and employees should be recognized not just for their own work but also for how well others are able to make use of that work. No more proving you are “the smartest person in the room,” a formerly common conference-room tactic at the company.

Lester noticed the shift after rejoining Microsoft last year. Colleagues had quiet conversations with each other to smooth out disagreements after tense meetings. People asked questions about the direction of projects and were given answers about strategy.