In a letter to season-ticket holders, suite holders and sponsors, the Baltimore Ravens believe the national anthem protest is one of the reasons why 

"The numbers [of no-shows] are higher, and it is noticeable," Cass wrote in the 656-word letter. "There are a number of reasons for the no-shows, but surely the one-time protest in London has been a factor."

The Ravens' first protest as a team occurred in London on Sept. 24, when more than a dozen players knelt during the national anthem before the first NFL game of the day.

The Ravens knelt again at home before next week's game. Fans at M&T Bank Stadium booed the players when they took a knee.

The Ravens have not since protested.