Follow all the developments on the NFL's open market with our up-to-the-minute tracking of 2014's free agents. More ...
Sproles turns 31 in June and showed subtle signs of decline last season. The extension should take him through the end of his NFL career as long as he makes it through the next three years in Philadelphia.
The addition of Sproles will allow coach Chip Kelly to go back into the laboratory the next couple of months and concoct more exotic formations on third downs and in the all-important two-minute drill.
What we wonder is if it will make sense to take a game-breaking LeSean McCoy off the field in key situations, only to see Sproles lose his mismatch capabilities as he gets deep into his thirties.