GREEN BAY—At first blush, it’s as though a player like Darren Sproles defines the term “X factor.”
Philadelphia’s veteran running back and return dynamo is one of the smallest players in the NFL at 5-6, 190.
He’s not his team’s primary ball-carrier, yet, he has four rushing touchdowns.
He’s also not the primary pass-catcher, yet, he averages a robust 12.2 yards per reception.
Now in his 10th year and with his third team, he no longer returns kickoffs, but he leads the league this season with a 17.0-yard average on punt returns, with two long TDs.
Then again, to call him an “X factor” unfairly undersells Sproles’ impact on games. That impact is not only pivotal, it’s constant – constant series after series because he can handle the ball in different ways, and constant week after week because he never stops doing his thing.
“The guy’s a game-changer,” Packers cornerback Tramon Williams said
Packers  wrote: