This seems to me as if it as a pick designed to make an immediate impact for next year. RBs can certainly do that, as well as any players in a draft. As impressive as Lawson is, I suspect that any LB coming into the NE system is going to have a steep learning curve, and any rookie, even a smart kid with obvious gifts, will be at least a year or three off from having that impact. I had thought the Pats would trade down, but they must have felt strongly that Moroney would be gone by then. I don't know much about him, and will be curious.
I also agree that it might indicate a possible trade for a WR in the works.