Last year was a terrible year for Vezenkov for a bunch of reasons and he was still -0.9 BPM and -2.2bpm. Brown was dogshit last year in general and worse for us, but the 2 previous seasons he was a -0.5 BPM for Denver while doing their defensive matchup work (a -1.0 BPM) and a +0.7/+0.2 the year before.
Obviously neither are ideal starter, but both are professional enough and do enough professional things to be the 5th best guy on the floor with the starting unit and not weigh them down.
The guy you want to trade Brown for (Caleb Martin) had a -2.0 BPM and a -1.5 EPM last year. Very similar calibre of player to the two guys we already have on the roster.