How many do you expect to see? I am seeing around 44% of shots taken being 3 pointers when set to -1...Is that normal for a SF?

The main factor is the defense's positioning -- you'll take more threes the farther off the ball he plays.  Also depends to a lesser extent on the SF -- if he has a high PE and low LP, he'll "look" for outside shots a little more.  Also depends on your team's passing -- if they're more adept at getting him the ball, then the number of "good" looks he gets from behind the arc may go up.
Just curious -- who are you referring to?  Manly seems to be taking about 22% 3's...

a minus one for a player is relative to his own normal baseline, so if the guy is normally a heavy perimeter shooting, he's still going to shoot quite a few, but just be a little more selective.

thx for input...makes sense..I just think the scale should go from +5 to -5...because I don't want the guy I am referring too to shoot 44 3's out of a 100 shots..I would like that more around 20...problem is that -2 is almost like turning 3's off and minus 1 is what was stated above....just seems like a huge gap

Just curious, but is it Bosley?  And if so, why would you WANT to reduce the number of threes he shots when he's hitting over 40% of them? (Mind this coming from someone who also wants more gradients of choices on the three point settings)