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New Stat:
The conventional data on team first downs isn't very compelling. Check out our attempt at accurate moving the football ratings that had the Super Bowl teams ranked #1 and #2.
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Accurate First Down Conversion Numbers
Everyone readily accepts that being able to move the chains and keep a drive going by picking up the first down is a big deal in the NFL. However, until now we've been hampered by conventional stats that don't get to the heart of the matter.
Using total first downs can often be a misleading gauge of which team was moving the ball more effectively since a team can go seventy yards for a touchdown in one play, but would only get credit for one first down. At the same time the "third down conversion rate" stat, while useful doesn't address the issue that the better offensive teams reach a third down situation less frequently -- the good teams are picking up the first down on first or second down and not forcing the issue with a "must convert" situation.
To rectify this problem with the official NFL stats, we've created new "moving the football" ratings. Basically we track what percentage of the time a team picks up the first down (or scores a touchdown) on each down in a series, and also tally up what percentage of the time that a team starts off with a fresh first down that they will pick up the next one (note: within three downs, fourth down conversion was excluded since it is a more dependent number).
Please note that an offensive team can pickup a first down through a penalty (for example, a pass interference call) which we count in the stats. As a result of this and some other adjustments, our 3rd down conversion percentages will not match the official NFL stats -- ours are more accurate!
The theory is that this way it doesn't ultimately matter how many downs it takes to obtain the next first down, it simply says "you got the ball, did you succeed in moving the chains?"
The following table then shows the First Down Pickup Percentages for each down in series play, as well as a net rating taken from the series offense number minus the series defense number.
