this article was posted at soaring cafe. there, the pilot who
actually flew the flight commented, saying:

"I’m pretty sure I didn’t ask Corey to pull up and then dive to put
slack in the rope on release. We don’t do that at Beloit and its not
necessary with the Tost release on the Grob 103. ‘Much more likely he
was too low on tow for a safe release and I asked him to move up into
a proper high tow position before releasing."