Once upon a time the greatest run in Kansas City Chiefs franchise history was a 76-yard run by Steve Bono. That is still probably the best run in Chiefs history but Alex Smith put up one of the best we've ever seen by a Chiefs quarterback with this 49-yard run.
Alex later ran in a touchdown. He had 69 yards rushing in the fist 18 minutes of the game. Not a bad day.
If you don't know my Steve Bono reference, check this out: