Maybe he gave her a swingsetter for christmas.
There is a commonality among most of his big name students.  Look at golfdigest swing sequences and look at els, scott, and wie.  You will notice ONE person besides his students who has a straight rear elbow at immpact, I believe it was moe norman, EVERYONE else has more rear elbow bend at impact.    Is there a relationhip?  I think it might have something to do with it.