Honestly doesn't matter much.
This sums it up. I think people are trying to squeeze another inch or two out of Tatum so that they it can somehow be justified that we play him out of position as a big.
Tatum is a wing. A wing with nice length, but a wing. He is not a big. The Celtics play a lot with 1 big. That seems to work fine in today's NBA but if the other team plays with 2 bigs, it creates mismatches (going both ways). This is all still true whether Tatum is 6' 8-3/8" and listed as 6'-8" or if he is 6' 8-7/8" and listed as 6'-9".
I never understood why many seem to want to take one of the best young wings in the NBA and turn him into a PF. The solution to the Celtics lack of a decent PF is not to try and make Tatum a PF. The solution is to get a decent PF on the roster (because yes, sometimes you need 2 bigs on the floor). I just don't get this.
QUESTION: Do you consider Giannis a wing or a big?
I consider Giannis a natural big and within bigs I have him as more PF than C. The best scenario for a team would be to have Giannis play as a big and have actual wings play as the wings around him. Doesn't mean the team wouldn't play "big" at times and put Giannis at a wing position but to me, that makes no sense and isn't something Milwaukee did much at all last season according to 82Games. Milwaukee played the most last year with Bledsoe-Matthews-Middleton-Giannis-Lopez. That was their core line up. Giannis was the PF. Middleton and Matthews wings.
I apply the same kind of logic to Tatum. He is a natural wing. That is where he will contribute the most to the team. If the team had decent bigs, there would never be any reason to play Tatum as a big. Teams play a lot more these days with only 1 big, nothing wrong with that, but playing that way doesn't make Tatum a natural big. Miami played a lot (second most common line up) with Adebayo and Robinson as "bigs". Does that make Robinson a big? No, that is just a 1 big line up. Miami's number 1 line up was Adebayo and Leonard. 2 bigs.
I would be happy to see a Celtics roster that had enough talent in their bigs group that Tatum never "had" to play PF. They may choose to play with 1 big at times, with or without Tatum on the floor, but Tatum is a wing. We are better when Tatum plays as a wing. And if we had better options at PF, Tatum would never play PF. I don't want to play all the time with 2 bigs but I do believe you need to play a fair amount that way. For the Celtics, it isn't choice, we don't really have a legitimate starting PF, we have to play with 1 big most of the time. But that does not make Tatum a PF. We just choose to play without a PF.