Darrius Heyward-Bey in the slot? Sounds like a horrible idea on the surface, right? Typically, slot receivers are smaller guys with good hands. DHB is clearly neither of those. He is 6'2", catches the ball with his body and jumps to catch every pass. But, I still think he may be better suited for this position.
Ideally, DHB will progress to an outside threat. He has speed to get downfield and has the size and hops to go over corners to snag a pass. One big quality keeps him from doing this though. He has shown zero ability to track a ball and make adjustments when it is in flight.
I wouldn't want DHB to make a full-time switch to the slot. The lack of hands and jumping thing mean this team needs a more consistent option there. Still, I would like to see him learn the position, and get some snaps there. I think it will put him in a better chance to succeed.
DHB is much, much better when the ball is not in the air for a long time. In the slot, passes are going to come to him quick and won't require him to adjust to the ball. And that leads to the part of the move that I think would have the most potential is once he gets the ball.
"-" is a load to bring down. On the rare occasion he does catch a ball, corners just bounce off of him. If the Raiders can put him in a position where he is lined up inside and isolated on a corner and/or find him a little space, they can hit him on a quick pass and watch him run for extra yards.
This would not only gain a few easy yards from time to time, but also help build up his confidence.