I've only seen three USC games this year because they're hardly ever on TV and you have to pay some stupid subscription price to watch games on the school website, but here's what I've noticed so far about OJ Mayo, particularly after Saturday's game against Arizona State (which I attended in person).
His strongest quality right now is his on-the-ball defense. He really gave Derrick Rose problems earlier this year and he was flat-out man-handling ASU's point guard the three or four times he was asked to guard him. He keeps his arms up all the time and at 6'4" he's got as long a wingspan as any point guard in the NBA. Twice in five minutes he ripped the ball out at half-court for an open layup. He moves around picks quickly and anticipates passes well enough to get a hand on a lot of them.
He's playing mostly SG this year so he doesn't get much chance to bring the ball up, not to mention USC's offensive game is so inept that it doesn't even really matter who brings the ball up because they just pass around the perimeter anyway. There's only a few chances when you really get a chance to see what Mayo can do as a playmaker, but so far I've been very impressed. Taj Gibson is a good defensive player but he's got particularly terrible hands for catching passes. Mayo will fire the ball inside a couple times a game for what should be an easy layup but the ball will be bobbled and lost out of bounds. He's racked up a number of turnovers this way that are more the result of his teammates than poor decision making. And keep in mind this is from the SG position. He's not being asked to run plays most of the time, but his court vision is good enough that he finds open teammates with passes anyway.
It's hard to judge Mayo's ball handling from the USC games because he rarely holds onto the ball for more than a couple seconds. When he does make a move he can definitely lose defenders, but more often than not he passes the ball instead of taking advantage with a drive. I don't know why this is, but considering he made a name for himself with his ball handling ability as early as junior high, I suspect it's how he's been asked to play. I trust the skill is there because I've seen it in brief flashes. He broke free for dunks twice in the ASU game and it was evident you were looking at an NBA player. But those moments are so few and far between that it's hard to say if the effort is lacking or the desire. It's a legitimate criticism at this point that he doesn't look like he wants to take over games. Maybe that will change later in the season when the games mean more. There hasn't been much evidence of a killer instinct so far at USC.
I think it's pretty fair to say that Mayo won't have any problem with his outside shooting. In the games that I have seen his form looks good but the results have been mixed. Good against ASU and UCLA, not so good against Memphis. Three games isn't enough to really evaluate consistent shooting, so I'm relying a bit more here on reputation. He's the team's leading 3pt shooter anyway and he shoots the technical foul free throws as well.
After the last game, I'm a lot higher on Mayo than I have been. I can see why his stock is slipping -- he doesn't show nearly the willingness to take over and dominate games that his reputation would suggest, and that's what people look for in lottery picks. At times he looks like the most unselfish player out there, which can be frustrating when the team is struggling because he clearly has the skills to dominate if he wanted to.
I think the biggest question with Mayo is whether he can make it as an NBA point guard. From what I've seen, he has all the skills to be successful there, certainly defensively. He'll be a pain for any guard to play against. And that's the one area where he's shown the most consistency. He's shown good court vision, ball handling ability (in brief moments), and outside shooting touch as well so I think the biggest question is whether he has the personality to play the point guard position. As I mentioned before, USC's offensive system is awful so I don't expect he'll really learn to effectively run a team there. Some would say his high school career left little to prove in that area anyway. He's a lot more mature than people give him credit for and definitely a team player. He doesn't have the blazing speed that seems to be more and more important in the NBA, but he's got size to compensate (think Chauncey Billups). I would feel pretty confident drafting OJ Mayo as the point guard of the future if he's still available.
(Note - I'm probably a little biased towards Mayo anyway concerning the USC connection, so you can adjust your opinions accordingly. For what it's worth I think Taj Gibson might be a nice second round pickup as a defensive role player. He comes up with a lot of rebounds that he shouldn't and despite the bad hands shows a surprisingly good touch on the midrange shot. He dominated Brandon Wright in their Sweet-16 game last year before getting in foul trouble. Davon Jefferson is still something of an enigma at this point. I think he needs another year in college personally, but if he ever puts it all together he could be a very good NBA player as well. Not a star, but a consistent starter. He does a little bit of everything. Scoring, rebounding, blocking shots. Gets caught out of position too much on defense though.)