A Closer Look at Todd Gurley’s Breakthrough

Stephen Gill

Five months ago, I wrote an article about Todd Gurley’s abysmal 2016. You can read the entire piece itself to hear everything I had to say (there was a lot… and you might want to read the introductory stage of the series it was a segment of to understand my numerical references). I’ll sum it up quickly: The Rams offensive line was atrocious, and Gurley offered quite little when provided his few opportunities.

I predicted Gurley’s heinous 3.2 yards-per-carry mark to improve in 2017, but not by too much:

“There are positive and negative ways to look at the future. On the bright side, there’s loads of room to improve if solely through regression to the mean, let alone through on-paper improvement to the offensive line. The bleaker outlook is that blocking will still probably be subpar, meaning the onus falls on Gurley to provide effective rushing production. Given his previous campaign, I’m not as optimistic about this happening as most are.”

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Well, fast forward one season and, as you may have noticed, Gurley has exploded. He scored the most points of any back (and in some PPC- and PPR-heavy leagues, of any player) in his 15 games of 2017. What happened? For one, his receiving production flew through the roof:

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That’s a huge jump. However, what surprised me more was how his rushing efficiency went from among the league’s worst (3.2 yards per carry) to among its best (4.7 Y/C). And that’s what I’ll be diving into today.

So, what changed in the rushing game that could cause a shift of 1.7 yards per carry? In short: almost everything. First, the offensive line got a lot more push. The Rams recorded 2.27 Offensive Line Yards per Carry (OL-Y/C for short – what it measures is self-explanatory) in 2017, an increase of 0.65 yards per carry from 2016’s 1.62 OL-Y/C.

Six or seven-tenths of a yard doesn’t sound like a big difference but putting that number into a rushing yards per carry context, it’s huge – almost two standard deviations better. Adding that amount to Gurley’s 2016 rushing would push him up to 3.8 yards per carry on its own. Of course that 3.8 is still not good, and still almost a yard below his 2017 mark. This is where Gurley, himself, plays into things.

In a few words, TG generated yardage much more easily in 2017. The prior year, he generated 0.89 yards per carry on “stuffs” (runs where the line did not open a hole for the back) and 2.89 generated yards per carry when he did find daylight, two bad numbers. Those measures jumped up to 1.41 and 4.78 (both pretty good), respectively. Mathematically, that’s a big impact:

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(RB-GY/C is running back generated yards per carry, which measures a back’s yardage contribution… one simple way to frame it is as total rushing yards minus OL-Y/C)

Add that .9 to the 3.8 we’d found by adjusting the offensive line’s performance and, hey, we’re at 4.7 yards per carry, Gurley’s exact 2017 mark. (Mind you, this adjustment won’t always be perfect – there are other factors to the equation that Gurley and the Rams OL kept constant.)

With the aim of applying this improvement to future situations, what caused these progressions? Maybe it was aggressive regression to the mean? Or it’s the case that players’ stats have little to do with one another, year to year? Well, we’ll see glimpses about the latter explanation further down the line this season, and more fully next year. But even without that data, I don’t think that’s the case.

This progression is easily explained, and wide year-to-year variation in these numbers would imply that players’ actual Y/C marks would also fluctuate wildly, which isn’t the case. On the other explanation, the marks shifted from well below-average to well above-average, which isn’t how regression to the mean works. Instead, I believe that basically everything in that offense genuinely improved.

The offensive line brought in two new contributors (including Pro Bowler Andrew Whitworth), each remaining 2016 member probably progressed, and everyone stayed on the field: John O’Sullivan had the lowest snap count of the five but played over 83% of the team’s offensive snaps in 2017. Offensive lines matter, and using early judgments from my data this year, it might even matter more than I thought.

Meanwhile, Todd Gurley returned to his 2015 form, with improved elusiveness (he doubled his broken tackle rate), better decision-making (he kept his eyes up more and cut down on poor decisions, qualitatively speaking), and more downfield potency (he generated ten or more yards on 13 runs, compared to just four in 2016).

Finally, I’m guessing Sean McVay’s presence did wonders. The passing offense turned from pitiful to pretty good, which likely took a lot of pressure off the running game. (My latest statistical effort, accounting for box defenders, is a work in progress for this off-season – so I can’t say just how much this helped.) I’d venture to say McVay called better run plays for Gurley too.

So, that just about explains it. Where do we go from here? How do we value Todd Gurley now? To answer those questions requires a thorough examination of his receiving production in addition to this investigation, so I’ll leave that part to someone else.

But looking at the rushing side, I’ll say this: The offensive line (using its 2017 state as an anchor) is pretty good and Gurley is between very good and great (think 75th percentile). This means that as long as this offensive line stays intact and the passing game holds up, Gurley’s running efficiency should be safe.

However, I wouldn’t take the former happening for granted. Whitworth turned 36 in December, and it’s unlikely that the Rams can sustain the sort of offensive line depth they enjoyed this season. I’d certainly expect more health problems than last year. The question there is more “to what degree do they get hit by injury, and what degree does that hit take on their run blocking?” than “will they get hit by injuries more?” Worst case scenario, the line bottoms out and drops his Y/C mark by over half a yard. Best case scenario, 2017 repeats. Obviously, there’s a lot of room between that ceiling and floor, and considering how Gurley improved with a better offensive line, the rushing game’s spread of outcomes is even greater.

A lot will happen between now and September, so I’m not going to unnecessarily project. But the takeaway remains that Gurley’s 2017 showing in the running game was entirely legitimate, so it’d be fair to anchor your expectations on that production and adjust according to the changes that have yet to unfold.


stephen gill