generally you can evaluate the efficiency of running (once upright) by the status of the free leg (the one not touching the ground) at the point the heel of the stance leg leaves the ground - which for the geeks among us is the point the extensor chain (hs, glutes, lats etc) begins to become inhibited by a reflex on the bottom of the foot. The further the knee is past the stance leg at this point the better because the free hip will then be moving upwards and releasing energy stored in the it band and glutes on the stance leg. If you look at bolt at heel up his free leg is way past his stance leg allowing him to use all that elastic energy - hence why he is so efficient and has great speed endurance (at least over the 100m).
As kk says the further the free leg is past the stance leg the less weight is on the stance leg and so it can begin to extend. However the ankle isn’t able to fully extend until it is way behind the stance knee (hip extension is first, then knee then ankle). So i agree with charlie, i think she looks pretty good in this picture and you shouldn’t expect ankle extension just yet - more likely as her free leg reaches it’s highest point (around hip height). The issue for me with her poor performance is with her drive and transition at the moment… We’ll wait and see what she does in germany tonight…