I've also been surprised that Brown isn't getting more minutes, so I agree with you there.
I'm not sure I'd agree that Brown is clearly ahead of Hayward now.
Over the last two months (Feb and March), the minutes per game are almost the same - Hayward has 25 mpg, and Brown 25.5.
Hayward is shooting 39.1% from 3, 53% from the floor, good for 11.6 points per game. 4 boards, 3.5 assists.
Over the same period, Brown has scored a little more, at 13.6 per game, but he's also taking more shots and shooting a lower percentage - 36% from 3, 48% overall. Brown has the same rebound total, but he's definitely less effective as a creator/ballhandler, with only 1 assist per game.
Brown is clearly the better individual defender, but I'd say he makes fewer headshaking mistakes in team defense/blown assignments.
Net, pretty close, different skillsets.
I would say that the defensive gap is pretty huge. Hayward misses his share of rotations too, and probably is the least effective defender of the four. He still looks slow laterally. Brown makes some mistakes, but his overall defensive impact is quite a bit better than any of the other rotation wings.
It also appears that the C's demand far more conservative play from Brown that the other three. He's not the playmaker Hayward is, but he is actually a better passer than Tatum or Morris. He gets the least touches, and it looks like the team keeps him on the shortest leash as far as attacking the defense in the half court.
Stevens seems OK with some questionable isolation play from just about all the other rotation guards and wings, but not Brown. I actually think that has been OK, as he has learned to minimize a bad tendency to sometimes plow into defensive crowds and expose the ball. I just wish we cleaned up some of the bad habits of our other players too, and get more consistent ball movement.