Wasn't Anthony Barr spying on him? I think so because Allen made him look silly in several occasions and there was no other vikes defender helping him.
I mean Allen jumped over him one play, beat him to the pylon on another one, stiff armed him, and then got a horse collar tackle from him as well. I may not know a lot about football but it sure looks like Barr's task was to spy on Allen and nullify him.