This is because the variation factors from one day to another may significantly influence the distances the football goes. Among these factors are: the weather and Danny's condition. For example: wind strength, wind direction, any rain influences the skid, etc. Condition example could be: Danny is more tired on one of the days and can't kick as strong.
We shall use yards as the unit here.. 3 feet is 1 yard, so we know that the ratio is now 1 yard to 7 yards. We can't reduce this anymore, so this is the final ratio.