According to Business Insider, the Athletic has a story that Fultz started changing his shot with Keith Williams on his own initiative prior the season.
I believe a couple of people here have a subscription to the Athletic so article can be found here: https://theathletic.com//238687/2018/02/13/sources-markelle-fultz-significantly-altered-his-jump-shot-over-the-summer/?redirected=1
I believe a couple of people here have a subscription to the Athletic so article can be found here: https://theathletic.com//238687/2018/02/13/sources-markelle-fultz-significantly-altered-his-jump-shot-over-the-summer/?redirected=1