I dont know how accurate this list is but Simmons season statistically is better than all these guys except durant, carmelo and beasley. Sully is on this list.
http://athlonsports.com/college-basketball/best-freshman-seasons-college-basketball-historyHis college numbers are most comparable to magic and duncan if you merged them. He's averaging Duncan like rebounds and points but not the blocks, but more assists but not as many as magic. There is no player like that. Lamar Odom was like 17 and 9 as a freshman and like 3 or 4 assists. Probably the closest thing but not as good.
20/12/5 is pretty good as a college freshman. He's a less flashy magic/duncan hybrid like i said without the shot blocking.
Brad Daugherty averaged 20 and 11 and about 3 assists and a block a game in comparison later on in his college career. As far as passing big men in nba history there aren't many who were better. Russell, Chamberlain, Cowens, Unseld etc..
Simmons is such a weird blend because of his height and ability to play like a guard. He's 6'10" and is averaging 5 assists in college and 12 boards, and 20 points.
I dont think players today are on that level of all time greats and numbers are skewed a bit sometimes but that's still pretty good.
Bill Russell averaged 20 and 10 as a freshman in comparison. Blocks were not counted. Michael JOrdan averaged 20 and 6 later in his college career. Different times and more 4 year college players etc. Different game. Different skillsets etc. Steph Curry really had some monster years statistically later on.
Marcus averaged 15, 6, 4 as a freshman with 3 steals a game and a terrible field goal percentage.