For employers, fielding an application from an employee who previously quit might feel a little like opening your front door to find a romantic partner who recently dumped you begging to be taken back: uncomfortable, awkward and just maybe tinged with a bit of hope. 

So is it worth considering an application of a former employee, or is this a case of too much water under the bridge? It depends, Abbie Shipp, professor of management at Texas Christian University's Neeley School of Business, told HR Dive.

There's no reason to automatically exclude such candidates. Based largely on a conception of the worker as flaky or disloyal, the stigma of rehire "is going away as we become more comfortable with people holding more and more jobs in their careers," Shipp said. "I think we've started breaking those hard and fast rules: you go to one employer, you're there for decades, you have a pension, the company takes care of you, you reward it with your loyalty. That's gone."

Shipp first noticed the boomerang employee phenomenon in 2005, while working with a consulting firm on a different project related to the workplace. At the time, she couldn't find anything in the academic literature on the topic; it was mainly discussed by HR professionals as a "new and innovative" approach to recruitment, she said. She was intrigued and marked the topic as one to return to in research in the future. 

It took a few years to come back to the subject, but in 2014, she and a team of researchers published their findings on boomerang employees in Personnel Psychology. They found that boomerangs tend to differ from "permanent alumni" (those who quit and don't come back) in a couple crucial ways.

First, boomerangs tended to leave more quickly. Permanent alumni, in contrast, often put in many years at the company before quitting. The latter "really had accumulated experience with the firm and realized, 'This is not a good fit for me' or 'This is not the right work group.' And they just couldn't ever really resolve that," Shipp said. 

Second, boomerangs were more likely to leave due to a personal shock — a sudden death in the family, for example, or a serious illness — or due to receiving a better offer and being tempted to go elsewhere. 

The circumstances surrounding resignation amount to a difference between being "pushed out" (due to dissatisfaction with the culture or other workplace-based factors) and being "pulled out" (due to exigent life events or a competing offer).

In other words, boomerangs tend to come back because they never had a problem with the workplace to begin with.

Boomerangs can come with several built-in benefits. "They return and not only do they have knowledge of their prior employer and all the social networking and the way things operate, but they've gone to another employer and broadened their skill set. They've broadened their years of experience and can bring back that learning," Shipp told HR Dive.

Of course, those benefits are limited by how long an employee is gone; an employee who takes a leave for six months to deal with a personal emergency and then returns will be far more ready to hit the ground running than one who leaves for five years and returns to a whole new team and technological setup. 

If employers are weighing whether to take a chance on a boomerang, there's one thing to consider first, Shipp said: "It's really important that the employee had great performance in their first period of employment."

While it may be tempting to assume the worker was initially shaky but may have learned and grown in the time away, past performance is the single best predictor of future performance, Shipp said, citing research by others in the field. 

With recruiters desperate for talent due to the current labor shortage, there's no reason to eliminate a boomerang candidate with a history of good performance — and some reason to believe they may be a better option. 

"If you're worried about loyalty, if you're worried about performance, then do better exit interviews," Shipp suggested. "But keep in touch with the people who were the good performers who did leave for reasons that weren't about long-term dissatisfaction."

Broader research is needed on boomerang performance overall, Shipp said. Some studies have suggested they perform better than before, some have suggested they perform worse, and some have returned mixed results. The results are likely contextually dependent, with different jobs or industries showing better performance over others.

As the boomerang phenomenon persists and is more widely researched, HR managers are likely to learn more about the worker type and what to expect. "We're still learning a lot about boomerangs," Shipp said.