I have been thinking about this for a while and decided I should at least start this hack and post on the forums for documentation/progress.
My initial thought process is as follows:
I assume the blood animation is a separate graphic and not an entirely new set of sprites (CONFIRMED)
Find the blood animation tiles in NHLPA'93 (DONE, most likely)
Trace and reverse engineer the code on a blood injury in '93 (current phase)
Bring those elements into '94
I think