April 11, 2021

GridIron365

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The Effect of Scrambles on DVOA Revisited

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Regular Football Outsiders readers know that 2020 introduced a new version of our DVOA metric. One of the main changes of this new version was to treat quarterback scrambles as passes rather than runs. I wrote a long article about this last offseason. Now that we’ve counted scrambles as runs for a year, I wanted to revisit the topic and look at how that changed the way we measured running games and passing games in 2020.

A reminder of what I wrote last year about scrambles:

Scrambles are pass plays, by definition. The quarterback scrambles for positive yardage when he’s under pressure or when all his receivers are covered. Sometimes he runs just because a big hole opens up in the pass rush and it’s going to be easy to gain yardage. But every scramble begins as a pass play. Scrambles are essentially the positive version of sacks… When we’re looking at how efficient each team is passing or running the ball, on offense or defense, we really should be looking at scrambles as passes.

Last year, to take a look at the effect of scrambles on each team’s running numbers, I had to re-run DVOA marking all scrambles as pass plays. This year, I had to do the opposite: I re-ran DVOA but changed all scrambles back to run plays, and then compared that to actual DVOA using the new formula. Once again, the definition of which plays count as scrambles is based on the official NFL play-by-play, rather than ESPN or SIS data. It can be difficult to discern what is and isn’t a scramble, especially in this age of run-pass options.

Houston had the most scrambles in 2020, with 62 of them, and the largest effect from having scrambles count as passes instead of runs in DVOA. Houston gained just 4.04 yards per carry on running back carries in 2020, compared to 6.37 yards per carry when Deshaun Watson was scrambling. Combine that with a huge efficiency difference, and the gap between Houston’s run DVOA with and without scrambles is over 10 percentage points. Without scrambles, Houston was the worst running game in the league (-28.0%). If we counted scrambles as runs, the Texans would have ranked 27th instead (-17.8%). Houston is one of seven teams whose rank in run offense changes by four or more spots when we go back to treating scrambles as runs instead of passes.

The Texans’ passing DVOA barely moves, however, because the efficiency on scrambles (30.7%) is almost the same as the team’s efficiency on other passes (23.5%).

On the other side of the coin is Tampa Bay. Buccaneers quarterbacks only scrambled six times during the regular season (four by Tom Brady, two by Blaine Gabbert) and none of those runs converted for a new set of downs although Gabbert did have a 16-yarder on second-and-20 against Detroit in Week 16. Tampa Bay is the only offense whose run DVOA would have been worse if we were still including scrambles as runs instead of passes, and their rank in run offense would drop from 10th to 16th. That’s because scrambles are on the whole very efficient plays. It helps that there’s no such thing as a scramble that loses yards, since those are all sacks. Overall last year, quarterbacks gained 7.1 yards per carry when scrambling after a pass broke down. The league ended up with 65.8% DVOA on scrambles.

Other prolific scramblers besides Watson included Russell Wilson, Kyler Murray, and Lamar Jackson, who each ended up with 50 or more scrambles. The league’s best scrambler of 2020 depends on which version of DVOA you want to use:

  • If you want to use team DVOA, counting scrambles as passes and comparing them to a baseline of all plays, the top scrambler was Buffalo’s Josh Allen. Although he scrambled a bit less than he did in 2019 (going from 43 to 29 scrambles), the Bills had 110.8% DVOA when Allen scrambled. Allen averaged 7.9 yards per carry on scrambles with two scores and 10 other first downs.
  • If you want to use individual stats, then we count scrambles as runs and compare them to a baseline of all quarterback runs. With a minimum of 10 scrambles, Taysom Hill had the highest DVOA on scrambles (59.1%) followed by Cam Newton (58.3%). If we want to look at total value instead, Russell Wilson led the NFL with 141 DYAR on scrambles followed by Kyler Murray (120), a surprising Teddy Bridgewater (94) and then Allen (79).

Here are all the team numbers by the old DVOA method and the current DVOA method. Red numbers have scrambles as runs, while black numbers have scrambles as passes. The initial sorting order is based on the change in each team’s run DVOA from the old method to the current one.

Baltimore stands out here because the Ravens had a lot of scrambles with a good DVOA rating, but you’ll notice it doesn’t have that much effect on their run offense DVOA. However, removing scrambles from pass plays would drop their pass offense rating from 17th to 20th. That’s because the Ravens have such a strong run/pass ratio compared to most NFL teams. With many more runs and fewer passes, the effect of moving those 50 plays from runs to passes is stronger on the pass rating than on the run rating.

Once again as in 2019, only three teams had a negative DVOA when scrambling. It’s three different teams than last year: Indianapolis, Cincinnati, and Tampa Bay. The Bengals are a bit of a surprise because there were a good number of scrambles there, not just single digits like Indianapolis and Tampa. The big problem for the Bengals was scrambles on third downs. Only two of Cincinnati’s two scrambles on third down were able to convert to move the sticks, although one of those was a 19-yarder on third-and-18 by Ryan Finley against Washington in Week 11. Also, Joe Burrow fumbled the ball away on a scramble on fourth-and-goal from the 3 earlier in that same game before his injury.

On the other side of the ball, Tampa Bay is once again on the extreme. Just like the Buccaneers weren’t good on scrambles, they also weren’t good against scrambles, allowing 8.6 yards per carry on these plays. Because their defense was so stellar against the run otherwise, the Bucs see the biggest difference between DVOA with scrambles as runs and DVOA with scrambles as passes. Here are all the numbers for defenses, same structure as the table above:

The Vikings were very good against scrambles the last two seasons (9.3% and 6.5%) and the Broncos were very bad against scrambles the last two seasons (100.0% and 115.6%). But those seem to be exceptions, with the year-to-year numbers overall not showing much consistency. For 2015-2020, the year-to-year correlation of offensive scramble DVOA is .18 while the year-to-year correlation of defensive scramble DVOA is .13. Obviously, the small sample size affects those correlations. The worst offensive scramble DVOA of the last six years belongs to the 2017 Chargers because Philip Rivers only scrambled twice and fumbled on one of those carries.

https://www.footballoutsiders.com/dvoa-ratings/2021/effect-scrambles-dvoa-revisited

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