Ordinarily, the jobless rate and wage growth are like two ends of a seesaw: When one drops, the other is supposed to rise. But that link seems broken, and like film-noir detectives, analysts have scrutinized hard-edge statistics and fuzzier psychological indicators for clues about why.

In the recession that began a decade ago, the businesses most likely to survive tended to be the most conservative spenders, said Douglas G. Duncan, the chief economist at Fannie Mae. That approach was rewarded and has now been reinforced, he said, helping to restrain the growth of full-time work forces and salaries.

Aon Hewitt’s annual surveys seem to bear that out. The practice of spending more on variable pay than on permanent raises took root in the 1990s, when growing competition from abroad increased pressure on companies to keep a lid on prices and production costs.

Pay-for-performance and other bonuses increasingly functioned as a release valve. Companies could offer more money to attract talent or when profits were strong, and pull back when business was slow.

After the recession, the trend accelerated.

“The response in 2009 was unlike any prior response to a recession or depression in that organizations actually reduced salaries, they didn’t just freeze them as a means of allegedly avoiding greater layoffs,” said Ken Abosch, a partner at Aon Hewitt. “I think there’s been a lesson learned from that.” That lesson: Stay nimble.