It's remarkable how quickly Jaylen Brown has caught up to Avery Bradley in terms of both defensive and offensive prowess. He is almost exactly where Avery was last year in PPG and RPG (16 and 6) -- with AB now returning to his career average in rebounding this year (3). Avery was 26 years old last season -- in Year 7 of his career. AB worked his butt off to become a 16/6 guy. Jaylen is already there (we'll see if it sustains) in Year 2, just turned 21.
The defense as described above in this thread has also leaped dramatically to the point where he is considered by some here already on par with (or nearing) AB. And at 6'7" and uniquely athletic he can clearly be even more versatile with who and how he defends.
Jaylen's growth this year has been shocking to me. I know some here saw it coming, but I'm amazed. Hope it lasts.