I've been watching 49'ers since 1957.
Moss is Irvin, Bruce, Clayton, Larry, and Owens level for sure.
He's well above lots of others. Brown is only a possession reciever, and FredBlitz might be better.
On the 49'ers, Moss is no where near the level of any of those guys, because he doesn't make the effort to go for a ball that is not perfectly thrown to him...like Vernon.
Mario, Crab, and that other tight end would sacrifice their bodies to make the EFFORT to catch the ball.