Nique was a way more dominant scorer than Jaylen. Brown is better than McDaniel.
I think Brown is close to Jimmy Butler. Look at their stats.
Brown Butler
Position Guard / Forward Guard / Forward
Scoring ~23-26 PPG ~21-23 PPG
Rebounding ~5.5 RPG ~5.5 RPG
Shooting ~49% FG ~49% FG
Jimmy could sometimes take over games though more so than Brown.
However, Butler's teams were always much worse when he wasn't in the game. He has generally had an elite or borderline elite on/off differential. He improves every team he is on in large part because of the stats you don't show i.e. 4.4 apg to just 1.6 tpg. A 2.75 assist to turnover ratio is fantastic as is his very low turnover rate. Butler generates as many steals i.e. 1.6 as he commits turnovers. He also doesnt commit fouls at just 1.4 fouls per game. Butler plays winning basketball on both ends of the floor. He always has. Brown does not. Brown's impact to winning is basically non-existent because he doesn't play winning basketball. He is a very good player, his skill set just isn't conducive to winning. That doesn't mean you can't win with him as Boston has obviously done that, but plenty of teams have won with non-winning players on their roster even in starting roles. We saw this year what a Jaylen Brown led team looks like i.e. lots of stats and regular season wins, but limited post season success.
That's way too broad of a statement. Brown doesn't play winning basketball? He's won a championship and earned a finals MVP. He's in an elite group of winning players already.
I think Butler in his prime probably had a greater overall impact on his team than Brown did this last year, but claiming that Brown doesn't play winning basketball is not only untrue, it undercuts your points here.
An over-reliance on advanced stats is a market inequality right now in the NBA. Atkinson's quote before game 4 about how they should be up 2-1 in the series according to the stats shows this tone deafness in the advanced stats community. I think your insistence that the Cavs would tie the series in their two games at home after the eye test showed multiple problems with that theory like: 1) Harden collapses in big games, 2) Mobley clearly struggles with physicality, 3) Mitchell did not look like himself 4) the Knicks stole the Cavs soul in game 1.
I think advanced stats are helpful, especially with players like Butler who has good-not-great counting stats, because they reveal a true superstar career impact. They show a path forward. They help you focus on the winning processes, but the game is played on the court.