In his methodology, wide receivers are weighted more heavily than running backs or tight ends. So, the Bills' strongest skill player, James Cook, contributed less to the overall ranking than the Bills' mostly underwhelming group of receivers. He also used recent performance history, and players such as Dalton Kincaid and Curtis Samuel had down years last year.
If his methodology is accurate, imagine how good Josh Allen and the offensive line are to propel the Bills into being one of the top ranked offenses in the league.