Once you create that 2nd tier, my bar gets lowered a lot.
My unofficial threshold to be honored would be something like: key and/or highly recognizable contributor to winning teams who represented Celtics basketball (whatever that means). When I think of the team during a specific era, is this player one of the first players I think of? When I think of that player, do I think of him winning as a Celtic?
I'd be okay with Walton (even though less than 2 years in total games played), Ray, Rondo, Isaiah, Smart, Horford in that 2nd tier. When I think of any of them, I think of them winning with the Celtics. When I think of the Celtics during their eras, I think of them.
Tiny Archibald, when I think of him I don't think of the Celtics, when I think of the 80's Celtics, I don't think of him (well before my time though). But he was a 3x All-Star with the C's and won a ring. He's in.
Borderline: Antoine. Individual success with 3 All-Star appearances, and more playoff wins as a Celtic than Isaiah, but when I think of him, I don't think of Celtics winning (although I do think of him giving Pierce that speech to spur the greatest 4th quarter comeback in playoff history). Also don't associate his style/image with "Celtics basketball".
With my low bar, there can be a lot of "well what about him?" If Walton is in as 6th man, what about Posey. If Rondo is in, what about Perk. If Smart is in, what about Bradley. What about Celtic All-Stars like Kyrie or Kemba? They're all some combination of not here long enough (Posey), not memorable enough (Posey, Perk, Bradley), not associated with winning (even if contributing to playoff runs) (Kyrie, Kemba, Bradley), not properly portraying the image of "Celtic basketball" (Kyrie).
Low bar to be honored, very high bar to get in that first tier though. Moranis's first tier looks good to me, though Roy's more generous one looks good too, ha.
