Edit: Just noticed your updated post about Rozier 
Thanks. I think it's a bit of hyperbole to say that he has more potential than smart over about a half-hour of total play, but he's certainly not as useless as I thought.
On separate topic: you know what, we should just start Hunter, Young, or Clarke at SF. It is at possible at least in theory that they could guard players in the SF position. If they can't, at least they don't completely mess up our tactical structure like these weird permutations of lineups Brad is putting out.
If we start a kid at SF, maybe the starting lineup gets punished a bit against teams with good offensive options at that position. On the other hand, we get to keep the bench rotations the same and aren't forced into the frankenstein's monster lineups that kill our offense completely for three~four minute stretches throughout the game.
And who knows, maybe the minutes make it click for one of them and then we've got a huge windfall on our hands.
To be honest, I've been saying this about Rozier since draft day. Before I saw him play even a minute in the NBA or D League.
When you look at Rozier's college highlights, you can see the potential just dripping off him.
Things like:
1) Body control and his ability to finish tough shots around the basket
That's such a big thing for an NBA guard these days. Just a very explosive athlete, and yet he has the physical strength to be able to take a hit, and the physical length (6'8" wingspan from memory) to be able to get his shot off. So many highlights were you can see him taking hits, distorting his body, and somehow making the shots. There have been NBA guards who have really excelled as scorers despite not having a good jump shot (e.g. Wade, Rose) based purely on their ability to finish with contact around the basket. For an NBA guard to be an effective scorer these days, those skills are so important - and it's something Smart doesn't really have. Combine that with Smart's lack of jumper and it makes it hard to envision him ever becoming more than just an average offensive player.
2) Midrange game
Again, looking at those college highlights I was really impressed by Rozier's ability to his tough midrange jumpers in a variety of scenarios - contested, fadeaways, off the dribble, with contact, pull ups, etc. He wasn't yet constent enough with those shots in college, but the fact that he has the raw ability to make all of those types of shots is huge because 'where there is smoke, there is fire' as the saying goes - if his has some naturally ability to hit those shots already, then he has the potential to become a great midrange scorer with experience. This is another aspect of Smart's game that just isn't there, and really never has been.
3) Quickness with the ball
All through college Rozier showed the ability to be explosive with the ball. He's got an extremely quick first step and a solid handle, and is extremely good at changing speeds, changing direction and stopping on a dime. It's those talents that allow him to be so adept and getting to the basket pretty much at will, and that's another very important talent for a guard in the NBA game. If you can blow by your defenders on a consistent basis with your dribble and quickness then you can create all kinda of trouble for opposing teams - think: Isaiah Thomas. Yet another talent that Marcus Smart doesn't have. He just doesn't have that explosive first step, or the ball handling ability.
4) Three point potential
Rozier has never been an elite three point shooter, but he's been a competent one. He shot 33% from three over his college career (on over 3 attempts per game) and is shooting 34% from three in the D-League (on over 5 attempts per game), and he shot 40% from three in Summer League (on 3 attempts per game). He gets good elevation on his shot, he jumps very quickly, and he has pretty solid form based on the eye test. He hasn't played enough NBA minutes for his NBA stats to mean anything yet, but definitely has the potential to develop into a decent (perhaps even good) three point shooter - something Smart might one day do, but hasn't shown he's capable of just yet.
The above criteria are pretty much ALL you need to become a very dangerous scorer at the NBA level, so Rozier has all the tools.
I would say his PG skills are slightly better than Smart (better ball handler, about on par as a passer) which is impressive given Smart has almost two full season of experience under his belt now - versus Rozier who has barely played.
Factor in his defensive potential (lateral quickness, length, leaping ability, determination, motor), and his talent as a rebounder, and you have one very talented kid.
Even on draft day I thought Rozier had slightly higher upside than Smart (but also higher risk). By now I am extremely confident that Rozier is going to become a significantly better player than Smart.
I think Rozier has legit star potential. As I said in my previous post, I see him as a bit of a merger between Isaiah Thomas' offensive skillset and confidence, combined with and Avery Bradley's defensive skill set and determination. Put all that together and you have one hell of a prospect.
Don't be surprised if Rozier is taking over Bradley's starting spot a year or two from now, and maybe even Thomas' in time.