Who's the best/worst free agent we've ever signed?

[cloudwasher]

I was thinking about it on the drive home from work the other day, and the players with whom the Texans have had the most success have been through the draft. I dont know if anyone has thrown this question out there recently, but since we're entering the long boring stretch of the offseason I figured I would.

I was hard pressed while thinking about it to decide who is the best and the worst free agent acquisition that the Texans have ever signed? For the sake of making it interesting lets say that players obtained through a trade or in the most recent offseason (since we obviously dont have any games of them in a Texans uniform to judge them) off the table as far as consideration goes.

Im honestly not sure who I would pick for the best (part of the reason I decided to post this).... As for the worst, I would say Ahman Green. Fairly large contract with nothing but a few unproductive, injure prone seasons to show for it.