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The Secret To The Rams Blocking Success

As you may have heard, the L.A. Rams had 5.49 adjusted line yards per carry this season, the most for any offense we have ever recorded. Josh Hermsmeyer, however, thinks that says less about the Rams' offensive line and more about the coaching abilities of Sean McVay. Hermsmeyer took a modified version of ALY and adjusted it for defensive men in the box (which is data we didn't have when ALY was invented) and finds that while this year's Rams were excellent, they were not the best of the last 20 years -- that honor goes to the 2012 49ers, the team with Colin Kaepernick and Frank Gore that lost the Super Bowl to Baltimore.

More notable than Hermsmeyer's results, however, is his process. He finds that the number of defenders in the box doesn't just have an impact on the success or failure of a running play, it appears to be virtually the sole determining variable. It almost doesn't matter who's carrying the ball, who's blocking, or who's making the tackle, only how many bodies the defense has available to clog running lanes:

In fact, if all you know about a running play in the NFL is the approximate field position of a team and the number of defenders near the line of scrimmage, you're able to predict the leaguewide yards per carry with an extraordinarily high degree of accuracy: 96 percent of yards-per-carry totals are explained by the offense's field position and the number of men the opponent has in the box. How many defenders are in the box is almost certainly the most important factor in determining rushing success in football, so it follows that we should try to account for it.

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9 comments, Last at 02 Feb 2019, 9:30pm

1 Re: The Secret To The Rams Blocking Success

Read this earlier, glad to see it given Extra Point status. Are you going to looking into whether this methodology can be brought into FO stats? If the conclusion holds up it should provide a further way to grade the quality of the running game of teams against each other.

2 Re: The Secret To The Rams Blocking Success

This is definitely a step in the right direction, but if I read it correctly, the are just using offensive personnel as a proxy for defensive alignment, which is better than nothing, but still isn't taking a full bite of the meat. No, defenses didn't take the same approach to the box when the Vikings lined up in 11 personnel with Adrian Peterson and The Ponderous One in the backfield, in 2012, as they did with The Vikings in 2014 in 11 personnel, with Matt Asiata and Teddy Bridgewater in the backfield, and my point is not that the Vikings line in 2012 was good, as Adrian Peterson rushed for over 2000 yards. It may sound crazy to say the MVP's performance was substantially underrated that year, but I believe it to be the case.

5 Re: The Secret To The Rams Blocking Success

Yes, it seems like there are a lot of numbers in the background here that didn't make it into the article. It would have been cool to see, for example, what the % of Rams rushing attempts vs. 6-man boxes were relative to the rest of the league. That would have also helped paint a more complete picture of how big of a factor playcalling is having on their rushing success, since they still finish as 5th best team in the last 10 years in their box-adjusted ALY metric. Great insight though, and I'm sure it will be a great starting point for them, FO and others to dig in further.

4 Re: The Secret To The Rams Blocking Success

Is there not a problem here that number of men in the box is going to co-vary hugely with a whole bunch of other probably relevant factors, making the data massively confounded? I mean, being able to make predictions is all very well, but it would be great to understand the causal mechanisms.

8 Re: The Secret To The Rams Blocking Success

The amount of consistency of gain based on where on the field the play was is interesting too. Presumably a lot of that is to do with how much more tight to the line defensive players will tend to be at the ends of the pitch compared to when in the middle (and so many coaches just run to make sure they can punt when inside their own red-zone, defensive players and coaches must sell out more to stop the run on those downs).

9 Re: The Secret To The Rams Blocking Success

Bill Barnwell's preview column for ESPN has a nugget related to the discussion in this article: Gurley was the only back in the NFL this season who had more blockers than defenders lined up in the box on his average running play, +0.15 blockers/defenders in the box per rush. Again, would love to see league-wide numbers for more context, but he does note that this is the highest for any back with >10 carries/game in the last three seasons in which the data is available.