I completely understand what people are saying - obviously the level of competition was not high, as we really didn't face a single team that has playoff potential.
At the same time though, guys rarely put up dominate preseason numbers unless they are legit NBA stars. Guys like Paul George, Anthony Davis, etc. The guys who put up very impressive preseason numbers often (not always, but often) end up becoming quality NBA players.
For example, James Young dominated the D-League, but his preseason numbers still sucked. Perry Jones is a fringe NBA-caliber player and yet he was practically nonexistent in the preseason. That was against the same third string nobody's that Mickey and Rozier dominated.
This is why I look at stats of guys like Mickey and Rozier and see them as promising signs of their talent.
I think Mickey is a legitimate rebounder and shot-blocker, and I think that those two skills (at the very least) will translate to the NBA. In this league if you're a big man who can defend and rebound at a high level, then that is usually enough to earn you a solid role. Just look at guys like Nerlens Noel, Tyson Chandler, DeAndre Jordan, Omer Asik, etc. Those guys are hardly quality offensive players, yet have all started in this league at some point or other.
I also think Mickey has a decent chance at becoming a productive offensive player as well, as I think his length, athleticism, soft touch inside and solid jumper gives him the potential to become a solid threat in both the pick-and-roll and pick-and-pop game.
People point to size as a reason why Mickey wouldn't become much in the NBA, but look at somebody like Thaddeus Young - the guy is the same height as Mickey with nowhere near his strength or length and Young's only real advantage is three point range (which Mickey may well develop one day).
Also I'm not sure why people consider mickey skinny. He's 6'8" and 238 pounds at only 7% body fat. There's more muscle on that frame than you think. Also look at guys like Anthony Davis and Dwight Howard looked like when they were in college, as opposed to their second or third year in the NBA. It's almost certain Mickey will further fill out that frame.
I don't think Mickey will ever be a star, but I can see him developing into (at least) a Brandon Bass calibre player.