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.

Fewer Pointy Edges

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.

New Evaluation System

Christi Olson thrives on competition. But she'd prefer that competitive drive be focused on increasing Bing's market share against Google, not on pitting herself against her teammates.

The marketing leader rejoined Microsoft two years ago after nearly five years working in search marketing at Decide.com, Expedia and other West Coast companies. She had been approached by several people within Bing, and eventually her soon-to-be manager organized a panel of current employees to explain to her the changes they were seeing.

When Olson worked at Microsoft in the early 2000s, there was pressure to make yourself look better than others. It wasn't official, she said, but "if you wanted to stand out, that's how you would make yourself stand out."

The controversial "stack rankings" review system, which directly compared one employee to another, was replaced in 2014. The new review system, current employees told Olson, graded you a few times a year not just on your own work, but also on how you built on others' ideas and how they built on yours.

"It's much more conversational," Olson said of her reviews in the last two years. "Whereas previously it was like doing an end-of-year business review starting with achievements in quarter one." Now she has one review dedicated to her career development, and at least two more to review the past few months.

Some employees still criticize the new program, saying it's similar to the old system, just with a different name.

But for Olson, it has encouraged her to train other Microsoft employees on one of her specialties -- speaking at conferences. She is preparing to travel to Australia and London to provide public-speaking workshops for Microsoft employees so they can also represent the company at conferences.

In her previous time at Microsoft, it would have been difficult to convince her managers she needed the time and budget to host those workshops. With the new focus on developing others, she said, it was encouraged.

Emerging Technologies

Microsoft has long courted and encouraged employees to return to the company, said Chuck Edward, who is corporate vice president of its global talent acquisition. In recent years Microsoft has been in an especially strong position because of its rising stock price and word-of-mouth about the Nadella culture shift.

More broadly, recruits are taking renewed interest in the company's emerging technology, such as its Azure cloud-computer service and HoloLens augmented-reality technology.

Sharad Sundaresan left his job as a development lead of SQL Server at Microsoft in 2005 but kept an eye on the company as he traveled from Amazon to Yahoo to Roku, among other companies. Through the late 2000s, he noted, mobile and social networking were kings, and Microsoft hadn't found a foothold in either.

"It felt that Microsoft was sort of treading water a little bit, figuring out what it wanted to do next," he said.

But then he noticed an inflection point. The Surface tablet was released in 2012. Azure, originally released in 2010, began to gain steam, and HoloLens entered the market in 2016.

Sundaresan started hearing from friends within Microsoft -- the work was becoming more collaborative, and Microsoft was pushing the use of its software across myriad devices, even those created by competitors.

Intrigued, he came back to the company last March to work on 3D and augmented- reality technology.

"It's a super early space," he said. "To be part of it and help shape it going forward sounded exciting."

Group Accountability

The culture shift is still trickling through the company of more than 126,000 people, Lester noted, about a year after he rejoined Microsoft.

"You can't move a culture in any direction quickly when there are that many people a part of it," he said. "Obviously, a culture is the people."

But, slowly, he believes, it is taking hold.

Nadella's appointment factored heavily into Lester's decision to return to Microsoft -- the CEO had been Lester's direct manager in an Office group nearly two decades before.

As soon as he heard Nadella was on the short list to lead the company, Lester was sure he would be chosen. He recalled Nadella's confidence in meetings, his ability to recall technical details of every project, his patience in explaining decisions.

Lester is trying to practice the same patience, though he admits he slips at times. A few weeks ago, he grew frustrated in a meeting with his direct reports, disappointed by a few steps that had been missed on a new employee's initial training.

Afterward, one of his employees approached him and said "we get the message, and you're right, but I think some of the people in the room were upset that you were so frustrated about it."

It was true, Lester thought. He sent out an email to his team saying he thought he could have done better. That email, his employee talking to him -- none of that would have happened during his first stint at Microsoft.

"These are not just permitted conversations now," he said, "they are expected conversations."