Washington has been primarily known for his return abilities in Seattle as the Seahawks have been content to hand the ball to Marshawn Lynch, but Washington was used as a change-of-pace back at times. He made his debut in the NFL as a fourth-round pick in the 2004 draft by the New York Jets.
Washington spent four years in New York before he was traded to the Seahawks for a fifth-round pick in April of 2010. In his three years in Seattle, Washington was used in the same way, mostly on special teams.
Since his NFL debut, Washington has carried the ball 473 times for a total of 2,213 yards and 16 touchdowns for an average of 4.7 yards per carry. He has also racked up 1,127 receiving yards and two touchdowns. His biggest contributions, though, have come as a kick returner as he has 6,315 return yards and eight touchdowns.
The Patriots have been famous for making use of running backs and receivers who don't quite fit in elsewhere in the league and while he is sure to return kicks and punts for the Patriots, it wouldn't be surprising to see Washington contribute in the backfield a little more often while in Foxborough.