For nearly two calendar years, there is a numerical benchmark that’s failed to be cracked. Some got close. Some inched within a few feet. All fell short.

For 35 consecutive games the Seahawks have not allowed an individual opponent to rush for 100 yards. It’s the longest active streak in the NFL. It’s one of the longest this century. And it helps tell the story of a defense that has been among the best — if not the best — in football during much of that stretch.

Now comes perhaps the biggest challenger to the streak, a guy the Seahawks know well and has proved to be the best free agent signing this offseason. Here comes Kenneth Walker III to face his old friends who get to tackle him for real.

“He’s killing it right now, having a great year,” defensive tackle Byron Murphy II said.…