I know this is a click bait-y title and there may be flaws in my reasoning but hear me out.
The celtics play their best when either Tatum or Brown initiate the offense. The Celtics also play their best offense when either Tatum Brown or Richardson get to attack off of a primary action. My favorite possible lineup out of the entire roster is Richarson, Brown, Tatum, G. Williams, and R. Williams. This lineup can switch and has decent rim protection beyond Rob as both Grant and Richardson are good weak side helpers.
Yhe general idea of this lineup isn't necessarily supposed to be the starting lineup, but I think this lineup in particular should have the most minutes, and should finish games. Beyond this I believe this concept has a few interchangeable parts given that Brown and Tatum are always the PRIMARY initiators. line ups such as [brown/tatum] Jrich Grant horford rob, [brown/Tatum] Langford Jrich Grant [horford/rob], Brown Tatum Langford Grant [rob/horford].[player/player] indicates interchangeable.
The key to all of these lineups is there is some sort of rim protection, either brown or Tatum or both initiating, switchable 1-4, and an additional spacer/secondary attacker in Grant Langford or Richardson. Another sneaky important thing that makes these lineups work is both Rob and Horford are decent passers. you could include Pritchard as a spacer but due to his size he doesn't quite fit the idea as I don't want him switching too much. I think Nesmith also fits well into this concept if he can find his stroke and/or stop getting lost occasionally on defense.
Well what about Smart and Schroeder? Here's my thing I already wrote an article about those two so I don't have a whole lot to say. Just kidding this is completely about those two. The both take up a lot of minutes on this team and with the concept outlined prior, their minutes should at the minimum change in nature if not in number.
I think they are both good players. When Schroeder's pull up/ turnaround is going he can give you 20-30 and he fights on defense. Smart makes at least one play a game in defensive and loose ball situations that is outstanding, usually more, and when he has a rare efficient night he is the ideal star role player. But usually smart is just elite defense and below average offense.
The Big difference between smart and Schroeder is that smart is most effective playing on secondary or tertiary action either as the last man on a perimeter swing or driving and finishing/ throwing the lob. Although smart does it too, Schroeder often stops the ball when he gets it and tries to set up a pick and role and probes to beat his man, if he can't he has below average vision and often doesn't hit the big he has gotten open or he takes a tough pull up that does go in from time to time.
With all that in mind I think we can sneak smart into the lineup concept outlined earlier. I think with either JB JT or both on the floor Smart should be asked to work as a slashing, posting, spot up 2 gaurd. Unfortunately I think Schroeder is his best as a lead ball handler and in my opinion he should be considered behind Brown and Tatum for that position. In my opinion Schroeder should be limited to working in double big lineups when only one of brown or Tatum is on the floor.
I am not super clear on what is possible trade wise, but if it was possible to get a gaurd with a shot and a swingman with a shot for smart and Schroeder I would go all in and lean into the two of the three Tatum Brown Richardon at all times concept. I think for both brown and tatum to reach their full potential they both have to be comfortable being the focal point of the offense a la every nba star with ever.
I think the Tatum Brown Jrich Grant Rob lineup is not only quite solid defensively, it is one of the better offensive options the celtics has. If a player like Nesmith could be shooting 45% for three or if they could get any shooter taller than 6'4" more reliable than Richardson from three the lineup is even more viable.