Heath Sherman, who led the league's running backs with a 5.2-yard rushing average, carried 6 times for 12 yards.
The offense has improved considerably because of Keith Byars and Heath Sherman.
Andrew Toney, the fullback, was a holdout until this week, and Heath Sherman will start for him.
The reserve fullback Heath Sherman broke four tackles on a 19-yard, fourth-quarter touchdown run to give the Eagles a 14-6 lead with 10:30 to go.
The first came on a trick play, with running back Keith Byars throwing a 9-yard pass to Heath Sherman.
Heath Sherman gave the Eagles a superb ground game, with Philadelphia outgaining Washington by 66 yards to 19 in the quarter.
Heath Sherman rushed for 71 yards and Hebron added 46 to help give the Eagles the rushing advantage, 162 yards to 52.
Heath Sherman, the featured running back, is averaging only 2.8 yards a carry.
That group included Anthony Toney, a 227-pound running back who has been displaced the last three weeks by 190-pound Heath Sherman.
Heath Sherman gained 82 of his 105 yards in the second half.