But for every JT, there's a Cooper or even Lowe (I'm talking 2015), guys that can do the clean up work and offer something else. The Broncs have TPJ, Su'A (will likely get there), Haas and (pre-injury Gillett, although different and often unused skill set).
Everyone say Carrigan will be better (and he may well be) but Arrow has the runs on the board. And even after all that, look at the price tag attached to a JT2 / TPJ (eventually) compared to a Parker. TPJ has also proven he can play anywhere in the forward pack. Arrow isn't even just a workhorse lock, he hits hard (and sticks) as well as having an offload that can become better yet (given his age).