Devers did get better technically, I feel, as she aged and lost a bit of speed as she used to get so close she was forced to kick the lead leg out though did even later but I felt she was a better hurdler having more room to execute the TO.
Sally already has a lead going into H1. Her initial acc. and then takeoff into H1 sets up such a good race for her. Not that H1 alone wins for her but she gets out so well and the takeoff is fantastic that it leads to high velocity going into H2 and so on.