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 70 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. We also tally up what percentage of the time a team starts off with a fresh first down and gets the next one. (Note: within three downs, fourth down conversion was excluded since it is a more dependent number).
An offensive team can gain a first down through a penalty (for example, a pass interference call), which we count in the stats. As a result, our third down conversion percentages are more accurate than the official NFL stats. This way it doesn’t ultimately matter how many downs it takes to obtain the next first down.
The following table shows the top 10 teams in the 2002 NFL regular season in first down pickup percentages, sorted by a net rating taken from the series offense number minus the series defense number. Each down is listed with the percentage of the time that the team either made a first down on offense or gave up a first down on defense.
What jumps off the page is that the Super Bowl winner Tampa Bay ranked first, while listed with the percentage of the time that the team either made a first down on offense or gave up a first down on defense.
What jumps off the page is that the Super Bowl winner Tampa Bay ranked first, while Super Bowl runner-up Oakland was second. Anytime a statistic correctly tabs the two teams that reach the big dance we pay attention. In fact, through the past few years, six of the eight teams that reached the championship game were led the conference in moving the ball. The "true first down" numbers nailed the SB teams 75 percent of the time at the start of the playoffs.
Tampa Bay’s defense, while best at stopping the opponent short of the first down, dominated most strongly on first down plays. Teams could only manufacture a new first down 13.9 percent of the time. Indeed on third down conversions, Tampa Bay’s defense was only No. 2 in the league.
On the other hand, Oakland’s offense was most superior to the rest of the league on second down plays. The Raiders had a 41.6 percent conversion rate, higher than many teams on third down.
Using these numbers to predict spread outcomes, 1 percent of net "moving the ball" rating is worth one point of spread value works effectively, particularly in week 10 and on matchups. (Ex: Tampa Bay at +8.5 and Oakland at +7.4 on a neutral field, we’d predict the Bucs to win by 1 point.)
Through two weeks this season, the leaders Buffalo, Tampa Bay, San Francisco and Indianapolis. Bills and Bucs in the Super Bowl? We’ll update this stat when more games are played.
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