According to new research from professors at Georgetown, George Washington, Emory and Iowa State University, white position coaches and assistants in the NFL are more than twice as likely to be promoted to coordinator than their black counterparts, regardless of their performance, experience or coaching background.

Christopher I. Rider, who is a co-author of the study, says he was surprised by the magnitude of the "white coach effect" among aspiring coordinators, who aren't subject to the Rooney Rule.

"Just focusing at the top is unlikely to effect much change," says Rider, an assistant professor at Georgetown.

The study's findings are especially stunning because they account for the reasons typically used to justify the race gap. Rider and his co-authors tracked the careers of more than 1,200 NFL coaches between 1985 and 2012 and tested a number of factors to see whether they could explain why white coaches -- who constituted about 72 percent of the pool -- were more likely to climb the ranks. 

They also considered which positions the men coached when they entered the league, perhaps the most common justification for the lack of black coaches. According to their research, quarterbacks coaches are more likely to become head coaches than, say, receivers or running backs coaches. And because white players are more likely to play quarterback (a recent study found that black high school quarterbacks are 39 percent more likely to be asked to switch positions when they enter college), they are also more likely to coach the position, and then possibly become coordinators, and so forth. They accrue privilege from the moment they step foot on a field, and it only accumulates as time passes.

The white coach is 114 percent more likely to become a coordinator.

"Black coaches are less likely to be promoted than white ones, independent of their first position, their current position, their employer, their prior experience, their education and their age," the authors wrote.