The list is long and undistinguished.
I'm going with Eddie George. They signed him in 2004. Apparently, he retired in 2003..
When he was with the Oilers/Titans, seven out of his eight seasons he rushed for well over a thousand yards. The other season he rushed for 939. He was a four time Pro Bowler, he was a thousand yard rusher the previous season.He had never nissed a start in his first eight seasons.
In Dallas he carried as many as 31 times and never got a 100 yards in a game.....not one.He looked old, tired and completely uninspired.
2nd place - Mike Vanderjagt, kicker....He was one of the best in the league, played for the Colts, once he got to Dallas he turned into Maher.