The question is how did the fragment end up striking the curb. There are possibilities but no definite answer. I suspect this will remain and unsolved mystery, one of the few involving the JFKA.
It would have exited over the top of the windshield and gone on to hit the curb. The two large fragments found in the limo had gone upward upon exiting Kennedy's head. And they went there separate ways laterally. The one that hit the chrome piece was not far off from exiting. If it was a fragment that struck Tague , it would have had to go between 5 and 10 degrees to the left in order to hit Tague. I can't remember the figure and I can't check it out now because I've just been updated to the most recent version of GIMP and I have don't feel like trying to figure out how to use the measuring tool tonight. I'll delete this version tomorrow and download a much older one.
On edit: I just used the measuring tool in the latest version of GIMP. The fragment would have had to "deflect" 6 degrees to the left in order to hit the curb near where Tague was standing