During that period, sales of NFL merchandise rose three percent, according to the report.
The Baltimore Ravens, which saw its sales rise during its run to the Super Bowl following the 2012 season, were the only team to endure a larger decline than the Redskins.
"People are having a second thoughts about wearing a T-shirt with the logo or name that it has now been called racist," said Matt Powell, senior analyst for SportsSourceOne.
Washington's win total also declined substantially from 2012 to 2013. In 2012, led by rookie quarterback Robert Griffin III, Washington won the NFC East title, while in 2013 the Redskins finished 3-13.
The team's name has increasingly come under scrutiny from Native American groups, lawmakers, media members and other observers, who say the name is offensive and racist toward the Native American community.
In June, The United States Patent and Trademark Office canceled six federal trademark registrations for the Redskins. Multiple print and television media members and publications have vowed not to use the name.
A letter signed by 50 U.S. senators and endorsed by majority leader Harry Reid urged NFL leadership to press for a name change.
Redskins president Bruce Allen responded with his own letter. "With over 81 years of tradition created by thousands of alumni and millions of fans, the Redskins team name continues to carry a deep and purposeful meaning," he wrote.
Washington owner Dan Snyder has repeatedly said he will never change the name.
- Chris Johnson