I did a little goggling :
from this site :
http://www.mnfarmliving.com/2017/01/whole-pork-loin.html
I guess that front end gets cut off , butterflied and sold as country style ribs , some time boneless. this cut has a lot of that darker meat
guess that's why I like the CSR so much !
if you are ever getting less than a whole P Loin get the hunk that's on the larger end , towards the head :
http://www.unclejerryskitchen.com/diy/butcher-whole-pork-loin/
the darker meat in on the L of the first pic
and on the R of the second pic of the whole loin
the 3d pic cut up is even more dramatic
look at those three chops on the R :
Good eating , set SV or a fast grill to rare.