The choice is whether to phase him out this year or continue to give him lots of reps, hoping that his presence will help in the playoffs.
Personally, I consider him our #5 WR (with our #6 even less likely to contribute).
Given how Vrabel trats other backups, it is not at all clear why this backup gets so many reps.
IMO, if our top 4 WR's are healthy, I wouldn't even have Williams active. When everyone is healthy, we have plenty of receiving targets. Giving Williams reps simply means that a better [player is on the bench. That is NOT the way of Vrabel. Consider how many starters who get 100% of the available reps or very close.
That being said, Boutte, Stevenson and Hooper have been injured. So, I can see Williams being active. It would be GREAT for Williams to be the first off the bench to backup Boutte. For the rest of this season, I think that Douglas is a better choice for that role. As a bonus, a spot on the active roster is opened up.