It is strange to speak of a player's floor as something that assumes both significant defensive improvement and significant shooting improvement. Why is it impossible that he never improves at all? What about only a little? What about a decent amount, but not all the way to Porter's performance? Why do you assume he'll learn to play NBA defense. He's terrible at it right now and plenty of players never figure it out. His steals rate is also a bad sign as to his instincts on that end.Maybe I am but again barring injury, I think Jaylen's floor is to be one of the best 3&D guys in the league. Assuming you agree that Jaylen has shown that he can play a pretty high level of individual defense like Porter (leaving out things like rotations, which the 'Zards didn't do very well), to turn Jaylen into Otto Porter basically means turning this shot chart
into this shot chart:
which doesn't seem very far fetched to me, particularly since Porter doesn't have much of a handle and his jump shot is more a product of hard work than great mechanics (https://theringer.com/wizards-otto-porter-jr-breakout-season-shooting-182800da9510).
And as for Stanley Johnson's second season, while I don't see him play at all, it strikes me as not a a good comp for two reasons: (1) he apparently drastically overhauled his shot before the start of the season, and (2) he was in Van Gundy's doghouse for at least a good bit of the year.
Maybe Porter is a bit optimistic but my bigger point is that athletic wings who can guard multiple positions and hit three pointers are incredibly valuable in today's NBA and Jaylen has already shown to me that he has the skills to be one of the best at that.
I like Brown a lot. I'm reasonably optimistic about his future. But, his floor is a lot closer to Gerald Green than it is to Otto Porter or Jae Crowder.