I’ve got some math I’ve done on the subject, but it’s not in front of me at the moment. In terms of sweeping statements though, blood warriors do a small number of wounds per point spent on them. For example, a BW 30-man unit costs 520. They do about 12 wounds, and dividing that out shows their wounds caused per point, in this case 43 points per wound. To put that into perspective, a Khorgorath is 18.4 points per wound caused, and that’s with his new nerfed price.
Calculating in buffs is helpful, but that tide raises all boats. It’s hard to calculate how saves allow them to fight again, and how Gorefists and fight-on-death come into play. With those caveats in play, blood warriors simply don’t measure up to virtually anyone else.