That's a bad idea. TBN Bloodspillers should be dps neutral, and they pretty much are right now. It's not perfect because of differences in things like fight length or number of TBNs, but the dps difference between never using TBN and using it a lot is almost non-existent.

It shouldn't be a noticeable dps loss because that just means DRKs won't use it (like Inner Beast), but it also shouldn't be a dps gain because that's just going to make DRKs sacrifice mitigation for dps. You'd have to use TBN every 15s to avoid losing some casts, and you'd end up not having it for tankbusters because you already used it 5-10s ago. Holding on to TBN for even a few seconds would be bad because it has such a short cooldown. The way it works now is fine: you can use it for every single tankbuster and as often as want in between, and you'll still end the fight with the same dps as someone that barely used it.