Brown (undisclosed) hasn't been participating in joint practices with the Buccaneers this week, Turron Davenport of ESPN.com reports.
Occasional rest days make sense for a star player who had offseason surgeries on both knees, but it would be odd to keep Brown out of consecutive practices this late in the summer unless there's some kind of problem at hand. Coach Mike Vrabel declined to elaborate Thursday afternoon, merely saying Brown is not available. The wideout presumably won't play in Saturday's preseason game at Tampa Bay.