By Michael Shapiro Buffalo’s star wide receiver is backing his brother in a ranking of the league’s top cornerbacks. Bills receiver Stefon Diggs is never afraid to be bold, and he didn’t hold back when assessing the league’s wide receivers and cornerbacks in a conversation with Sports Illustrated’s Alex Prewitt. Diggs, a two-time Pro Bowler, said in a story released Thursday he believes the NFL only has “seven to eight spicy receivers who can catch, can create separation, can run fast, can stop.” As for the league’s cornerbacks, Diggs is even less impressed, noting just three corners truly cov…