Jaylen Brown is 22 years old and has played three NBA seasons, and so far I personally do not feel he has shown enough so far to justify a max extension.
For Brown to justify a max extension (or close to it) I'd need to see "future All-star" when I look at him - truth be told, I just don't see that yet. I see Trevor Ariza - that's a nice player, but not a max contract player.
That said, many NBA players do not really break out until their 4th NBA season, so if I am Danny I want to hold out, see how things play out to start the season.
- If Brown comes out and really takes a huge step forward, then I'd be offering him the extension before the All-Star break.
- If he gets mid way though the year and looks largely like the player he was the last two years, then no
So for me, if I am Ainge, I'm holding out until at least a month or two into the season, to see exactly what Brown has to offer when given the opportunity to be a centerpiece of the team (as he will have that opportunity be this season).