You keep Randle and force Simmons into the SF role, you'll have ty spacing. In today's NBA, your SF NEEDS to have a 3 point shot. Simmons isn't a 3 point shooter. I also don't know why you focus on per game stats. This is 2016

Randle's lack of length, ty jumper, terrible defense and lack of playmaking will keep him from being anything more than maybe a high caliber role player. Look how Randle performs against front lines with length. Plenty of 2-9, 3-12, etc type of games.
Randle could possibly develop, but he plays for the franchise that is the worst in the NBA at developing young talent
If you get Simmons, I expect the Lakers to clean house and build from scratch. They'll possibly keep Russell because of the HS connection, though. But just because something worked in HS, doesn't mean it'll work in the NBA.