Yeah, the Williams comparison is very lazy. Only used because both are spectacular passers and both are white. It's predictible, and not very accurate or informed.
Not saying he'll ever be great, but Rubio's IQ is much higher than J-Will's. I have much more faith in him running a team than Williams. Furthermore, he's a much better passer.
Unfortunately, when it comes to discussing Rubio, the reasoned view of him is usually overshadowed by two other groups: The annoyed Americans, who irrationally dislike him and want him to fail, and thus declare him a bust; and the overzealous Europeans, who think he'll be a superstar, which obviously is no more accurate than the first group.
That's obviously a blanket statement and won't apply to everyone, but it's a shame that many seem to have lost all objectivity when it comes to him.