Making sense of Jaylen Brown's previous impact with Celtics - ESPN

If the Dallas Mavericks' infamous trade of Luka Doncic produced waves of shock and outrage across the NBA, then the Boston Celtics' trade of Jaylen Brown a year later was met with considerably more complicated reactions. Outrage, yes, from Celtics fans — but also a fierce debate about Brown's on-court value and broader questions about how to analyze players in the modern, data-infused NBA.

Brown is a five-time All-Star, a former Finals MVP and the sixth-place finisher in regular-season MVP voting in 2026, after he averaged a career-best 28.7 points per game. Yet, advanced stats were more skeptical of his stardom. The Celtics had a better net rating with Brown off the court than on it in seven of his 10 seasons in Boston, including each of the last four. (All on/off data in this piece comes from Cleaning the Glass, which strips out garbage time.)

With Brown poised to play against his old team for the first time on Tuesday (8 p.m. ET, NBC/Peacock) — and with the NBA's best current rivalry poised to begin a new chapter — it's the perfect time for a deeper dive into what exactly the gap between Brown's reputation and advanced stats means, and how it contributed to the summer's blockbuster trade.

Given the statistics explosion in the NBA's ongoing information era, it's easy to access on/off numbers for every player in the league. Based on conversations with both public and team-side analysts, here's the best way to understand how to interpret them.

Jump to topic:
The on/off basics
Interpreting the use of on/off
How on/off contributed to Brown's trade

A modern NBA front office is inundated with data about every player in the league. Points, rebounds, assists, shot quality, pick-and-roll frequency, isolation efficiency, jump