He had an undiagnosed rib injury. A negative x-ray by no means an absence of a rib fracture. So, you have to go by function. Is a player able to perform in an absence of analgesics? Miller’s ACL wasn’t seen on the most sensitive imaging we have, yet still had an ACL tear. No one was going to inject that knee with toradol, pat him on the butt, and send him back in.
Now, if a player has a known injury and it’s determined that playing through discomfort won’t affect the long-term prognosis, then inject away. You don’t do this clinically unclear injuries though.