Check out his stats below so far this season. His weakness last season was weak rebounding numbers for a sf(needs to add more strength). Numbers look much better so far (has had a 13 reb performance recently).
The bio on JJ
6'8" to 6'9" with 6'10" to 6'11" wingspan. Very good size for a sf. Has a body similar to Tashyaun Prince. Quick and is
A good athlete. High IQ player , with very good court vision. Slippery around screens with a reliable running floater. Solid Jump shot. Plays hard on both ends . good leadership skills.
Weakness: mainly needing to keep adding strength. With this will rebound and able to finish around the rim better.
Why over Brown- Brown is a terrific athlete that likes to attack the basket. He gets too happy attacking the basket. Jump shot, ability to identify the open man needs work. Also though listed at 6'7, looks more like is 6'5.
Why over Ingram- Ingram is a talent but is not very strong right now (rail thin) nor quick. Has a body and moves like Bruno Cabolco, but has more skills. The question is, what position does he play in the future? Who can he defend due to lack of quickness/strength? If there was no questions about his body/physical tools would challenge Simmons for the number 1 spot.
I think Jackson would be a solid fit under CBS. He also has the skills and desire to score (go off and score 25-30 points) but won't force the issue and find open teammates on the court.
http://www.sports-reference.com/cbb/players/justin-jackson-4/gamelog/2016/NBA draft highlights
http://youtu.be/ScqzPwsknn8