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Talking about continuity on the offensive line with Thomas Emerick of The Sporting News

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Seattle Seahawks v Chicago Bears Photo by Quinn Harris/Getty Images

On Saturday the Seattle Seahawks take on the Dallas Cowboys in a return to the playoffs after having sat at home during the 2017 postseason. A big portion of the credit in the team making its return to the postseason has been given to the offensive line, which was a much more experienced unit in 2018 due to both the return of J.R. Sweezy and the addition of D.J. Fluker.

To discuss the effects of offensive line continuity in general, as well as on the Seahawks revitalized run game, I reached out to Thomas Emerick, an NFL contributor at Sporting News who has done quite of looking into the value of continuity for offensive lines. I asked some basic questions about offensive line continuity in general, and then specifically as it pertains to the Seahawks.

He’s a quality follow on Twitter (@ThomasEmerick) and a big thanks to him for answering these questions for us.

Question: You’ve done a lot of research about the effects of continuity on the run game for offensive lines, and can you kind of discuss what you’ve found in terms of Run Continuity Projection (RPC) and

Answer: Like many measures, it’s especially helpful to have control stay in place over multiple years like offensive scheme/coach, OL personnel quality/fit, and featured back. You get some great case studies when these factors stay constant while offensive line continuity — or that OL/RCP number I’ve used to contextualize over the years — goes through significant change.

Lack of OL continuity adds an obstacle in accruing rush yards, though a rather high rate of the exceptions seem to come from teams with new head coaches. A successful change in offensive scheme seems to throw a wrench things when looking for correlation, just as it presents something new for opposing defensive coordinators to confront.

So to touch on this idea of new head coach bucking continuity trends, from 2011-2017 we saw 23 percent of teams roll in with a new head coach to start the season. But of rushers who managed to finish top 10 in yards behind OLs replacing multiple starters, 43 percent come from teams with new HC.

  • Teams that produced top 10 rushers averaged 3.56 returning OL starters, 3.7 for top 5. Remove teams w/ new head coaches from sample and it’s 3.64 for top 10 and 4.1 for top 5
  • Teams w/ bottom 10 @PFF run block grade 3.08, bottom 5 is 2.83. Remove new HC teams & bottom 10/bottom 5 is 3.13/2.88

Removing new HC teams from the sample, the multi-OL replacement rate for top 10 rushers then decreases by 23 percent. Not the most robust sample, but trying to work within stark change to practice restrictions in 2011 CBA, so then onward.

Also, here’s my record of offensive line starters based on how it shook out Week 1 this season. I went back-slash for players who were in line to start but weren’t cleared for Week 1 specifically — another complication for this metric. For quantifying OL continuity, I just counted the actual Week 1 starter as I had done for previous years.

In the case of RG Austin Blythe for the Los Angeles Rams he just kept the job after the starter’s suspension and it worked out, while Indy’s Joe Haeg qualified as returning starter when he filled in for LT Anthony Castonzo. With Jack Conklin, and he ended up recovering from injury enough to seize his RT spot for the Titans, but didn’t really find his peak form before hitting IR. Pat Elflein not being ready W1 was among many harbingers for Vikes’ line.

Question: Obviously, any prediction will have hits and misses since there are always unforeseen events that pop up that could not have been anticipated, but how accurate has RCP been during your time using it?

Answer: I think it adds good context at the extremes, largely for flagging players who could take a step back or forward in rushing production. Small sample stuff comparing whole OL units since the CBA — while factoring in noise of scheme and runner — but there was decent correlation all things considered in the first few years, particularly with individual rushing yards and Pro Football Focus run-block grade at the extremes. I detailed a couple examples from Arian Foster and DeMarco Murray before cautioning against CJ Anderson heading into 2015. It’s also interesting that the past 17 leading rushers returned majority of OL starters and 15 returned 4+. Last to buck this Priest Holmes ‘01, in the early stage for an all-time great KC unit.

After the 2015 season when Todd Gurley and Doug Martin managed to produce at an incredible rate given how hard they had to work for their yards, I began to find this metric equally if not more useful in just finding avenues to explore OL impact, and the overall context around rushing production. It’s best as an instrument in that regard, though there is value in the context it adds to other factors that have shown more predictive value for total rushing yards (like carry volume) or less value (probably previous-year YPC among others).

Question: Can you talk about RCP as it relates to the 2018 Seattle Seahawks o-line? And how does that continuity compare to Hawks lines in prior seasons?

Answer: The Seahawks avoided replacing multiple starters for the first time since 2014 — the year before parting ways with Max Unger and James Carpenter — as four returning starters gave them more than 2017 (2), 2016 (3), and 2015 (3). Marshawn Lynch landed top six in rush yards in three straight years prior while the Hawks emphasized starting OL continuity in 2014 (4), 2013 (5), and 2012 (5).

Here’s who I had recorded as returning starters for each team in Week 1, based on listed starters for that week at Pro Football Reference.

Question: Knowing that two of the Seahawks five current starters are free agents in the spring, what do things look like in terms of continuity for 2019?

Answer: With JR Sweezy and DJ Fluker UFA, George Fant RFA and Jordan Simmons ERFA, will be interesting to see who stays, as two qualify as returning starters between the four of them. I’ll be updating a bunch on this front now that regular season has ended.

Question: How does the way the Hawks have used George Fant as a sixth lineman affect the metrics going forward?

Answer: Fant would not qualify as returning starter for 2019 since he’d have to get >50% snaps or enter Week 1 as starter in 2018.

Question: Is your work able to track any of the individual player improvement over time as a younger lineman or TE gains more experience?

Answer: This purely tracks continuity, that sliver in the rapidly developing frontier of OL metrics. Early in my tinkering with this metric I had counted 250-plus run block snaps for TEs as partial credit in run-block continuity. Since TEs increasingly don’t need to be any good at run-blocking to be on the field, it didn’t seem intuitive to factor it in and standardize. So I am still looking for ways to improve it while keeping the scope in the best position parse meaning and context of OL continuity for rushing production. Just looking for more ways to peel that onion.

That is certainly some interesting data, and I appreciate Mr. Emerick taking the time to address these questions. The Seahawks successfully made it back to the playoffs this season, and the question is now what the team can do both this weekend in the Wild Card game, as well as into the future.