I never heard of any evidence that stated JonBenet suffered a severe blow to the head which killed her. Such a blow would have resulted in significant damage to the skull, I believe. The medical examiner would have recorded this fact. And yet, not a word has been whispered.
Also, why plug Burke into the picture when there isn't a single thread that traces anything back to him? Where is the probable cause that must be shown? Where is there evidence about a bat, a bat in his hands, a bat in her room, a swinging of the bat which killed her?
Well, that's a surprise to me. I'm no expert but the autopsy report (which is online and you can google it) specifically states that the skull was split wide open from front to back along the top right side. The coroner also stated that it was the skull injury that caused the death, not the ligature. He even goes on to say that the ligature was applied 10 - 45 minutes AFTER the head injury was sustained.
So, I don't know what you've heard but that's what the autopsy report said.
JonBenet was a public figure and as such her existence known to many with criminal and violent intentions.
She did have a cracked skull.
The blow occurred very close to the time of death, but did not cause death, she was strangled. Like someone was strangling and beating her at the same time.