OK, I'm game. I'll take a shot at it.
Lets first start by evaluating the conditions. The surface looks fairly smooth, and given the grayness of the light, it might also be fairly firm. The terrain does not look very steep, therefore these skiers are probably not going very fast. I will go with these assumptions.
I'm going to start with the skier in back-.
This skier tends to use a fairly narrow stance. The general fore/aft stance seems to be adequate, but possibly a bit toward the ball of the foot. Judging by the body position (square, but not rotated), I might believe that the skier has some reasonable guiding (steering) skills. From that stance, refined guiding is the mark of a "competent" skier.
But unfortunately, the narrow stance leaves the edging movements quite limited. The square nature of the stance also limits the degree to which significant angulation can be achieved, resulting of the "banked" attitude shown.
Combined with the forward weighted stance, its likely the tails will skid laterally to some degree during the second half of the turn, as the energy increases.
This skier would be approx a Level 7/8 in good conditions, dropping to a L6/7, with difficulty linking round turns with speed control, when it gets more difficult.
The skier in front-
This skier has a slightly more open stance. There is good symetry in the legs, as evidenced by the similar angles of both skis. But since there is no visible reverse camber in either ski, I don't believe the edges are holding adequately.
There is a slight amount of spinal angulation exhibited, as the shoulders are not completely perpendicular to the legs. This would also lead me to believe there is a very slight amount of counter existing. But not enough counter to provide any appreciable knee or hip angulation, which would be necessary to create more effective edging.
Because I suspect weak edging, then it follows that any guiding (steering) movements will tend to be skidded. But it is possible that the skier might be able to maintain a semblance of an arc with subtle guiding. But if the speed or pitch of the hill were to be increased, this skier would soon find himself sliding sidewards.
This skier might be a Level 6/7 in good conditions, and a L5/6 in difficult conditions, without suitable edge control.
I have no trouble putting both these skiers together, despite what I've said are the differences between them. It would not take long to get them both on the same page...
With both skiers, (if they agreed) I would approach them with some ideas as to how to increase their edging effectivness. Introducing some greater ranges of movement would facilitate stronger edge edge control. That would be followed by refining/adding strong guiding movements.
Thes are just a few ideas that came to my attention.