I think this exercise might be useful, but for a different reason. I think looking at the top shut down corners is more predictive of production by the teams 2nd receiver.
Look at Thursday's game. Chambers was shadowed by Ike Taylor (and doubled quite a bit). Look at the production out of the Booker/Welker combo...pretty good stuff.
If you have Chad Johnson, you're never going to bench him, regardless of who he is matched up against, so this exercise isn't going to be helpful from that point of view. However, if you know that Johnson is going to be matched up against a top shutdown corner, I think you would be more likely than usual to start Housh (just as an example).