GLENDALE, AZ - OCTOBER 01: Head coach Kyle Shanahan of the San Francisco 49ers talks with referee Tony Corrente before the start of the NFL game against the Arizona Cardinals at the University of Phoenix Stadium on October 1, 2017 in Glendale, Arizona. (Photo by Norm Hall/Getty Images)
LONDON, ENGLAND - OCTOBER 01: Referees take the field before the New Orleans Saints International Series game versus the Miami Dolphins on October, 1, 2017, at Wembley Stadium in London, UK. (Photo by Ricky Swift/Icon Sportswire via Getty Images)
PHILADELPHIA, PA - SEPTEMBER 24: referee Jerome Boger (23) reviews a play on the Microsoft Surface during the NFL game between the New York Giants and the Philadelphia Eagles on September 24 2017 at Lincoln Financial Field in Philadelphia PA. (Photo by Gavin Baker/Icon Sportswire via Getty Images)
