I think he's a younger version of Kris Middleton. He'll get craftier and perhaps improve his shooting to match KM over the next few years.
Both are 6'8". Middleton outweighs Tatum 222 to 208.
Regular Season Stats:
Middleton is a career 45/38/87% shooter. 4.4 rebounds, 3.2 assists, 15.7ppg, 31.7mpg
Tatum is a career 46/40/84% shooter. 5.5 rebounds, 1.9 assists, 14.8ppg, 30.8mpg
Those are kind of uncanny numbers in their similarity.
Middleton is 28, Tatum is 21. I can see Tatum making a few All Star teams, perhaps more than Middleton will.
I really don't think tatum is 6'8".
Watching him the last couple of plays he definitely looks taller then Hayward. Height-wise he looks to be somewhere between Theis and Kanter - I'm suspecting he has grown to more like 6'10" by this point. Even in the USA games he looked significantly taller and longer then guys like Middleton.
Also, while they may be similar players in terms of shooting ability, I think Tatum has far more natural talent as an outright scorer. I think his quickness, athleticism and ball handling ability make him far more capable in isolation situations where he's able to create his own shot or get to the basket with relative ease and finish over length. I also think he's got a much wider array of moves in the post and in the midrange area. By comparison Middleton has always seemed to me more like a catch and shoot guy who can also get his own shot off against weaker defensive players.
Personally, I think people are just expecting WAY too much from a 21 year old guy who is just entering his third year. This is like the year there Tatum should make major progress, and i expect him to have progressed significantly by the All-Star break and even moreso by the end of the season, but it takes time for young guys to develop.
Tatum has the benefit of having a plethora of offensive moves - the challenge for him right now is situational decision making. Knowing when to the the three, when to post up, when to attack the basket, when to go to the midrange game, when to move the ball and look for teammates, etc.
The talent is all there and is almost unlimited - but when Tatum struggles is when he forces ISO when he should be passing to the open guy, when he forces a drive into an overly crowded paint, when he passes up an open three, etc. When he makes the right decisions on the court he is really, really good. That's something that will just come with age and experience in the league.
People also have to understand that this is a Celtics team that is flooded with perimeter scorers - Kemba, Brown, Tatum, Hayward. These are all guys who, on many other teams, would be #1 or #2 options. With that many touches to go around, you probably shouldn't expect Tatum to come out and average 20+ this year. There are going to be games where he goes off, there are going to be games where other guys play big and he doesn't really need to take a ton of shots.