Fred Jackson has been playing on a sprained knee the past month, and it probably has cost him a quarter of a step, if one were to precisely measure his speed.

It hasn’t affected Jackson’s production. At age 32, speed is not the key to Jackson’s game, anyway. Balance is the quality that sets Jackson apart from most NFL running backs.

Jackson rivals Nik Wallenda in the balance department, and he proves it every week with his ability to stay on his feet and gain yards after contact.

“Since an early age, I’ve been blessed with the ability to have tremendous balance,” Jackson said. “It’s something that’s been God-given. I appreciate that. It’s one of the things that’s always been a tool of mine that I could always rely on.”

The latest example came on the game-winning drive in the win at Miami last week. The Bills faced a third-and-4 play from the Miami 28 with 2:37 left. Jackson took a pitch to the right and was met head-on by Miami linebacker Philip Wheeler at the 26. Jackson bounced off Wheeler to the right and was hit by cornerback Brent Grimes at the 23. Jackson spun off that blow and tumbled forward to the 18 for a 10-yard gain.

The Bills were able to run the clock down before kicking a field goal to win, 23-21.

With C.J. Spiller hobbled by a sprained ankle, Jackson leads the Bills with 380 rushing yards. Buffalo ranks fifth in the league in rushing.

Jackson is averaging 4.4 yards a carry. He’s averaging 2.7 yards a carry after contact, according to Pro Football Focus. That ranks third best in the NFL this season.

Jackson has been bringing the yards after contact for years. In 2011, he had an NFL-best 3.7 yards per carry – after contact. He averaged a healthy 2.9 after contact in 2010 and 3.0 in 2009, according to Pro Football Focus. Usually only three or four backs a year average 3.0 yards after contact or better.

Jackson says he doesn’t do anything special to enhance his balance. He doesn’t jump rope, walk a balance beam or do ballet.

“We do a lot of core work, and I think that’s the No. 1 thing that helps,” Jackson said, referring to exercises that strengthen his midsection. “But I’m not saying I do a lot of extra core stuff. I usually do whatever they assign me.”

Jackson has a natural instinct for anticipating contact and using the momentum from a hit to shift and stay on his feet.

“You go into contact knowing you want to play off the type of hit you get from them,” he said. “It all just depends on the situation. You do plan on that when you go into contact, knowing you can use their momentum or the momentum you have going in a direction to break that tackle.”

Bills running backs coach Tyrone Wheatley was pretty good at getting yards after contact. Wheatley gained 4,962 yards over a 10-year NFL career. (Jackson has 4,611.)

Wheatley says Jackson runs with determination.

“The No. 1 thing in any high-performance environment is competition,” Wheatley said. “Whether you’re trading stocks or racing cars – it’s competition. You have to be a fierce competitor. Anything being close to dead is the only thing that will hinder you from competing. That’s the element Fred has. He’s a fierce competitor.”

“Fred is a cerebral guy,” Wheatley said. “Where he may have lost a step speed-wise, his eyes and his vision and his awareness picks it up.”