LeBron James has been called a king, a superathlete, a traitor. And now that the basketball megastar has decided to return to Cleveland and the team he once abandoned, he’s earned a new moniker he may not even know about: boomerang.

That’s as in boomerang employee. And while few will do it with as much fuss and fortune as James, it’s happening more and more often.

There is no hard data on how frequently employers rehire workers who’ve left to go elsewhere, but “it is growing, and smart companies are the ones pushing it the most,” said Abbie J. Shipp, an associate professor of management at Texas Christian University. “We’re updating the image of what employee/employer relationships look like.”

Experts point to a number of reasons boomeranging is booming: Social media make it easier for companies to keep track of former employees, and it’s often cheaper to rehire them because firms can bypass the search process. There’s less risk, too.

Perhaps most important, the old idea of loyalty – from both worker to company and company to worker – has evolved, and employees change jobs and switch career paths more frequently than in the past, said Brian Swider, an assistant professor of business at Georgia Institute of Technology. So leaving a company no longer seems like a betrayal.

“Boomerangs are not common in the classic employment model,” said T. Brad Harris, an assistant professor of labor and employment relations at University of Illinois at Urbana-Champaign. “Companies used to have the idea that you need to instill fear in workers – you only have one shot here.”

That is no longer entirely true. For example, Swanson Russell, an advertising agency based in Lincoln, Neb., has about 150 employees, including 12 who left and returned. That’s “an all-time high,” said Brian Boesche, a partner and chief creative officer.

“People worked differently 10 to 15 years ago,” Boesche said. “Attitudes have changed.” In fact, the company recently posted a short video – as a recruitment tool – on its Facebook page consisting solely of interviews with workers who quit at one point and then rejoined the firm.

Harris was a co-author of a recent study – Shipp was one of the other authors – on boomerang employees, “Gone Today but Here Tomorrow: Extending The Unfolding Model of Turnover to Consider Boomerang Employees,” which examined an accounting firm of 15,000 employees, where, at the time of the study, 20 percent of the hires were people who had left and returned.

Those who came back more typically had formed a plan for what to do after leaving the job – a pregnancy, going to graduate school or pursuing a specific career goal – than those who quit and never returned.

What are the wrong reasons to return? You miss your friends, or you haven’t given your new job a fair chance, said Roy L. Cohen, a career counselor.

“If you left because of lack of growth opportunity, a boss with whom you had a rocky relationship or the belief that you were underpaid, there is no guarantee that a return will resolve your relationship beyond the initial honeymoon,” he said.

While some employers worry that allowing workers to leave and come back will create a culture where employees feel they can drop in and out at will, Shipp said there is no evidence of this.

“Those who had left once were not more likely to leave again than those who had never left,” she said. In fact, boomerang employees might, in some cases, be more satisfied workers, because “they knew all the good things and all the bad things and came back with their eyes open,” she added. “It was their choice.”

That was the case with Che Knight, 28, a senior account executive with the Boston public relations firm Denterlein.

In 2011, after working at Denterlein for a little more than a year, she made the jump to a rival company.

Knight said all the articles she read about how millennials advance in their careers urged them to keep their eyes open for opportunities and be ready to leap to other firms to climb up that ladder.

“So I thought my growth trajectory should be quicker and, when I was offered a promotion, why wouldn’t I make the jump?” she said. Although she initially applied to the competitor, it was “very aggressive” in recruiting her, she said.

She has been happily back for almost four years, but acknowledges, “I was very concerned about what my colleagues thought. I would be lying if I didn’t say it was a little awkward at first, but I don’t think there was any resentment.”

Not all companies are open to the boomerang idea. Bloomberg LP, a financial software, data and media company, is well known for its closed-door policy to former employees.

“There are exceptions if someone leaves for certain family situations, education, public service or military service, but not to a competitor “ said Ty Trippett, a spokesman for the company. “From the early days, the philosophy was very clear. If you left for a competitor, you were not welcome back.”