I am deeply confused by anybody who puts Marcus Smart above Jae Crowder on this list.
Aside from passing/playmaking I seriously do not think there is a single thing that Crowder isn't better at.
Not only are Crowder's basic box score stats an entire stratosphere above Smart's, but even his advanced stats relating to sheer impact (which appears to be the strongest argument that exists for Smart's contributions) are still far and away in favor of Crowder.
While Crowder is better than Smart, it's less ridiculous to put Smart ahead of Crowder than to put Brown, Tatum and Morris ahead of Smart as you have. By the way, most Smart supporters (me included) would disagree that advanced stats accurately value Smart's impact.
This is a prediction of how the players will rank this year, given half these guys obviously haven't played yet predicting is all we can do.
Brown showed flashes of two-way potential last year as a rookie, and arguably had just as much impact as Smart did in the finals against Clevleand, outside of Smart's one fluke big game. He's shown the ability to hit very difficult shots, the ability to shoot relatively consistently from three, the ability to rebound, score in transition and off the dribble, an flashes of defensive potential. This season he'll have a full season under his belt, I don't think it's unreasonable to predict that he could well eclipse Marcus Smart as an all-round player.
Marcus Morris IMHO is already above Marcus Smart, and I have no idea how you could argue otherwise. He's well acknowledged as being a very good defensive player, and has been especially highly praised for the impressive defensive job he did on Lebron and Kevin Love last season. He's also been a consistently productive offensive player averaging double figure scoring for his career on 43% / 35% shooting for his career, along with a career high 14 PPG last season - which is WORLDS beyond anything Smart has ever even dreamed of putting up. As a legitimate two-way threat every night who also offers superior physical versatility (duet o his size and length) I think it's pretty hard to argue that Smart is better then Marcus Morris right now.
Tatum of course is a controversial one. All we have to go off is college and summer league. But we have to rank him somehow, and he's got to sit somewhere, so this is where I'm predicting he'll fall. Up until now the most promising prospects Danny has drafted here since the rebuild have been Marcus Smart and Jaylen Brown - Tatum's summer league performance was worlds above what Smart and Brown managed in their rookies years, and IMHO Tatum has already shown more skill on offense AND on the boards then either Smart or Brown have ever flashed. There are a LOT of people out there who have sad Tatum has been the most impressive rookie so far in this incredibly stacked draft, and I don't disagree with them. While nothing is certain, if Tatum was getting starters minutes on a lesser team I'd predict that he could put up 17 points / 7 and a very strong push for ROY consideration. On this team he'll have less opportunity, but I still think he will cement himself as being the best offensive player on our bench (and possibly our 6th man and leader of the second unit) by the time this season is up. On a second unit that is currently desperately lacking in offensive shot creation, I rate that as being more valuable to this Celtics team then what Smart offers.
On that other hand Marcus Smart is a one dimensional combo guard who has been in the league playing starters minutes for three years and has shown close to zero progression, and has continued to prove he is one of the worst shooters among all NBA guards while continuing to chuck up 3-4 attempts a night.
He does what he does (defense, hustle) very well, but you always need to factor in what liabilities he brings along with that and those often offset much of the good he does. If this was a team where hustle and defense were all that mattered, then I'd be happy to rate him in the top 3 on the team. But it's not, so I didn't.
If Smart can come out this season and either (a) shoot a half respectable 3PT% and FG% or (b) shot chucking stupid amounts of threes then I would happily move him further up the list. Until then, I have him right where I believe he deserves to be.
If I were him I'd be looking very anxiously over my shoulder at Terry Rozier too, because Rozier has far superior raw talent then Smart does and seems to be showing more rapid signs of improvement - if he ever flips the switch and starts to do his thing with some consistency, he'll leapfrog Smart pretty quickly too.