From the Wrangor article: "Sarr connected on just 14-of-37 (37.8 FG%) attempts at the rim, per Synergy."
Given that his added bulk should lead to a higher FG percentage around the rim and an increase in rebounds, I don't think 10ppg is out of the question at all. I also expect him to shoot closer to his 70% high school FT percentage this year. It'll be interesting to see if the added bulk leads to a more low post centric game. Like most Euros, he seems to prefer finesse over power, so hopefully we don't cram a square peg in a round hole.
Where did you see his HS FT numbers? He shot 85% this summer at FIBA.