I'd say all of the above + with the tournament set up being alternate break.
I've lost count of how many times I've seen Allison on TV and her opponent is maybe a game or two behind, while Allison is on the hill, and they break n run to only let Allison get right back to the table and do win the match.
Allison and Karen, are probably 1 or 2 balls better than everyone else, and girls like Jeanette, Monica, Kelly, Xia Pan, are probably a half ball less than them.
I'd also say that Jasmin is probably even if not a bit better than Allison and Karen, mainly because she is so aggresive when she is at the table.
The main difference i see with alot of the girls is how strong thier saftey's are.