In other words, by moving one side of the pelvis behind the other, the front hip becomes abducted or flexed/abducted, and not purely flexed. (Anatomic flexion is moving the quadriceps toward the abdomen, not to be confused with dance terms extension, which often means the same thing)
This allows the back hip both lift and naturally turnout. Depending on the skill required, this may be a good or a poor adjustment.
While a martial artist would do well with this position, a dancer would need to compensate with a torso, if she wants it facing forward. In other words, she should need to turn the back shoulder toward the front leg, in order to square her position. An example of this would be Penche or Grand Jete.
If the torso to remained perfectly squared without spinal rotation, the back leg needs to turn out. This of course places more stretch on the 4 adductors and pectineus.
When tested, not everyone who can do a perfect TFS, were able to simply turn the rear leg out.