Jaylen as a shooting guard can credibly guard power forwards, even shut some good ones down(see Siakam, P., 2020 playoffs). Please point me to the other top level SGs that can do that.
This is why I question whether Jaylen is actually a shooting guard. Defensively he’s a 3. Offensively he’s more of a 3 too. That the Celtics have two such starters (the other being Tatum) doesn’t make Jaylen actually a 2.
Put another way — look at that top 6 Roy put out. If Jaylen played on any of the teams with the others, he’d be the 3 every time. Do that thought experiment with the others and you aren’t going to find someone else who always comes out as the 3.
You could say the same thing about the greatest SG ever. A couple of the greatest SFs ever could have the same thing said about being PFs. But if they play where they play, they are what they are.
Yeah, you can debate this all day, is Smart a PG, is Tatum a PF, and so on. Many players have the versatility to be more than one thing.
In Brown's case, I see him as a wing. In my mind, there are guards that are wings and there are forwards that are wings. And there are guards that are clearly not wings (White, Smart for example) and there are forwards who are power forwards and clearly not wings (Grant, Gallinari, maybe Horford). But in between this are guards that are wings and forwards that are wings.
I totally accept that Brown's natural position is guard wing or shooting guard and that Tatum's natural position is forward wing or small forward. The natural position is the position where you are going to get the most out of a player, definitely not the only position a player can play.
Many people comment that the old standard 5 positions don't apply anymore. I disagree to an extent, I think they still apply, they just don't always tell the whole story. To have to say a player is either a PG or a SG, for example, doesn't always work. Smart and White are both combo guards in my mind. They can play either PG or SG while never really playing either. The line between PF and C is equally blurry. Horford isn't really either while being both.