Their value will fluctuate every now and then, but will steadily climb over time.

FORBES: Why 756 Will Not Equal Millions

Since the fumble rate peaked at 4% in 1973, fumbles have declined steadily in the NFL. But come playoff time, everything from nerves to cold weather to aggressive defenders can create major miscues.

WSJ: New England Running Back BenJarvus Green-Ellis Has Zero Fumbles in the NFL