I mean you say stretch 4, but he's barely played the 4 this season lol. B-Ball Ref has him 85% at the 3, 14% at the 4 and 1% at the 2. Which from the eye test, is absolutely correct imo. He's defended up to guards like Mitchell far more than he's defended down vs bigger wings/bigs like a Siakam.
I would actually love to see him more at the stretch 4 with like Huerter-Monk-Fox at the 1-2-3 positions, but Brown has pretty much exclusively played him as a wing and at times the defensive stopper on the best perimeter player. That makes his season all the more impressive considering it's basically an entirely different position than he played at Iowa.