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How does the 49ers rushing game perform based on the size of the backfield?

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The 49ers run the ball out of multiple-back formations more than any other team, but is that the best course of action? We examine San Francisco's rushing success based on the number of running backs on the field.

Al Messerschmidt

Perhaps the biggest question surrounding the 49ers this offseason—at least in terms of on-field topics—has been whether San Francisco will rely on Colin Kaepernick's right arm more frequently in the coming season. In that vein, many are expecting more three wide receiver sets to take advantage of an improved receiving corps. But do we have any evidence that using 11 personnel would be an optimal strategy for the 49ers given their past performance?

One of the many benefits of Football Outsiders' DVOA metric is that because it assesses each play individually, it can be used in in all manner of different splits to analyze a team's performance in specific areas. DVOA splits based on personnel groupings are included in the annual Football Outsiders Almanac, which will be releasing later this month. So while we'll have to wait a bit longer to get the full data for the 2013 season, we can start to piece together the answer given the information currently available to us.

Earlier this month, Football Outsiders released data on each team's rushing success by the number of backs on the field. Now, some quick context surrounding the 49ers' run game before we get to those specific numbers. According to DVOA, San Francisco's rushing attack was far less efficient last season, falling from the league's third best rushing DVOA in 2012 to the 14th ranked ground game in 2013. As it turns out, a good portion of the reason for that decline was their performance in multiple-back formations.

No team in the NFL ran the ball with two or more running backs on the field at the same time more frequently—78 percent for the 49ers—than San Francisco did. Shocking, right? As previously alluded to, their performance took a dip last year, dropping from 0.4 percent in 2012 to negative-9.9 percent in 2013. How did that compare to the 22 percent of runs that came out of single-back formations? The 49ers posted a negative-1.1 percent DVOA on run plays with just one back on the field. That 8.8 percent difference was the 10th highest in the league and slightly above the league average of 5.0 percent.

Those of you who read my article examining San Francisco's 2013 run-pass ratio may be thinking that a large portion of those runs from multiple-back formations came as the 49ers were grinding out a lead and attempting to waste clock. While I don't have the details on how many of those runs came late in the game with a lead, I suspect you would be correct in that assumption. However, because DVOA compares each play to the outcome of plays in similar game situations, that should already be accounted for in the numbers. To put it another way, even though we should expect the 49ers to be less efficient on the ground when trying to run out the clock because the defense is gearing up to stop it, that drop in efficiency appears to be greater than the one your average NFL team experienced.

Getting back to the team's performance in single-back formations, this is now the second consecutive season in which the 49ers have been significantly better rushing the ball out of one-back sets compared with multiple-back sets. Gauging the passing game in single-back sets is going to be a bit more difficult for a few reasons, but none more important than the fact that the new group of wide receivers changes the calculus a bit. So if you're looking for evidence to suggest the 49ers should spend more time in 11 personnel, at the moment a more efficient running game would probably be at the top of your list.