What Changed in the Rush Game: Volume I

| January 15th, 2020

Chicago’s rushing attack was woeful in 2019, finishing 27th in the NFL in rushing yards (91 yards/game), 29th in yards per attempt (3.7 yards/carry), and 26th in success rate on rushing attempts (44%). All three marks showed a decrease from 2018, when they were 11th (121 yards/game), 27th (4.1 yards/carry), and 10th (48%) in those three metrics.

This happened despite having fairly decent consistency in personnel. The starting offensive line was the same (when healthy), and the Bears saw only three primary rushers in both seasons. Tarik Cohen and Mitchell Trubisky were 2 of the 3, with the main rusher changing from Jordan Howard in 2018 to David Montgomery in 2019.

Today I want to look at the running game from a variety of angles to try and figure out what changed to account for the dip in production.

Player vs. Player Comparison

Let’s start out by comparing each player from season-to-season. First, I’ll look at the players who accounted for the majority of rushing attempts each year: Jordan Howard and David Montgomery. Their usage and production was remarkably similar in the two seasons, as you can see in the table below.

Similar playing time, similar carries, similar efficiency. The two were basically indistinguishable from each other, at least on the surface. That really makes you question whether it was worth getting rid of Howard and trading up for Montgomery in the 3rd round last year. At least for 2019, the answer is a resounding no.

This post is focused on rushing, but look at those bottom two rows. One of the reasons to swap Howard out for Montgomery was supposed to be that Montgomery can feature more heavily in the passing game, and thus make the offense less predictable and harder to defend. That didn’t happen in 2019. One of Chicago’s big problems in 2018 was that they were too predictable based on personnel (Tarik Cohen = pass, Jordan Howard = run, Anthony Miller = pass, etc.). In 2019, the offense ran the ball 50% of the time when Montgomery was on the field and only 24% of the time when he wasn’t. For Cohen, those numbers were 25% and 52%. That’s too big of a swing in tendencies based on personnel.

OK, back to rushing. If nothing changed with the main runner, then it stands to reason that differences came in the complementary runners: Tarik Cohen and Mitchell Trubisky. A closer look at their stats, shown in the table below, confirms that to be the case.

Trubisky and Cohen were both more involved and more efficient as runners in 2018 than 2019. In 2018 they combined for 167 carries, while that shrunk to 112 in 2019. Cohen’s lack of carries is due to play calling, but most of Trubisky’s runs are scrambles, which means he was choosing not to run this year. Between the decreased rushing production and increase in sacks taken, I think it’s safe to say that hurt the offense.

The lack of explosive runs from this duo especially hurt, as Chicago had the least explosive offense in the NFL this year. I looked at this last offseason and found that explosive plays are highly correlated to points scored, and predicted the run game would be more explosive last year after replacing the decidedly non-explosive Jordan Howard. That did not happen, as Montgomery produced only 5 explosive runs (half of Howard’s 10 in 2018) and Trubisky and Cohen’s explosion vanished.

Last offseason, I looked at the running game and concluded Jordan Howard was to blame. Two of 3 runners had found success in the same system behind the same offensive line, so I concluded the 3rd runner was to blame. It turns out that was wrong, which is why the Bears are now revamping the coaches responsible for the run game this offseason. Time will tell whether that approach ends up being more successful.

Advanced Stats: Cohen

Now let’s look beyond the surface to some advanced stats that might tell us a bit more about what exactly in the run game did or didn’t change. We’ll start with Tarik Cohen. Stats about contact and broken tackles are from Pro Football Reference, while stats about fronts faced are from Player Profiler.

This data suggests to me that Cohen’s dip in production was mainly due to run blocking, not his effort or how the defense defended him. He broke tackles at a similar rate and picked up similar yards after contact both years, and actually saw fewer defenders in the box and more carries against light fronts in 2019 than in 2018. The dip in production here comes from getting fewer yards before contact, which is mostly not on Cohen.

Next, let’s look at where and how Cohen was tasked with carrying the ball.

Here we can see that how he was used didn’t change much. He mostly ran the ball out of shotgun, and was generally more effective there than running when the QB was lined up under center. This makes sense for a guy who’s decidedly not a power back.

Cohen had the same number of carries between the tackles each year, but fewer carries outside the tackles in 2019 (remember: fewer carries overall; the difference came entirely outside of the tackles). This resulted in more balance in terms of where he was deployed, but not more success. His efficiency inside the tackles didn’t change much, but he was much worse outside the tackles. Often runs on the edges can be just as reflective of blocking by WRs and TEs as by the offensive line (more on that later).

It’s also worth noting that these are small sample sizes (about 30-35 carries each), so it might just be noise that’s heavily influenced by 1-2 big runs.

Advanced Stats: Howard/Montgomery

Now let’s use the same approach to look at how Jordan Howard and David Montgomery were deployed in the last two seasons.

Just like above, we see many similarities between Howard in 2018 and Montgomery in 2019. In this case, they faced very similar attention from defenses (at least as measured by the average defenders in the box). Two other thoughts:

  • Montgomery got more yards before contact than Howard, a distinct change from what we saw with Cohen above. I wonder if this might have as much to do with the runner as the blocking. Cohen’s vision seemed to take a turn for the worse in 2019, while Montgomery is more elusive than Howard, which might lead to making the first man miss more often and thus picking up more yards before somebody makes contact with him. I don’t know if that’s true or not, but it seems weird to see Cohen’s yards before contact trend down while Montgomery’s trends up from Howard.
  • It also feels weird that Montgomery broke far more tackles than Howard but got fewer yards after contact. That might mean he had more instances of multiple defenders reaching him, where breaking one tackle doesn’t do much, or it could mean that Howard did a better job of finishing runs even when he didn’t get credit for breaking a tackle.

Like with Cohen above, now let’s look at where and how these backs were asked to carry the ball.

A few thoughts:

  • Again we see similar splits in terms of the amount of runs out of shotgun vs. under center, and again we see more yards gained per carry out of shotgun. This runs counter to the prevailing outcry among fans that the Bears ran it better out of I formation (which is under center) in 2019, but it could also be influenced by a number of short-yardage runs under center (where a 1-2 yard gain is the desired outcome).
  • The 1st real difference we see between how the Bears used Howard and Montgomery is in where they were asked to run the ball. Howard mostly stayed inside the tackles, while Montgomery was fairly balanced inside and out. This is one step towards making the offense less predictable; 2018 saw Howard carry inside and Cohen outside, while 2019 saw Montgomery and Cohen both fairly balanced. Now the next step has to be involving Montgomery more in the passing game.
  • Montgomery was actually more effective inside the tackles than Howard, but again we see a significant dip in production outside the tackles compared to 2018. That matches Cohen’s trend, and I echo my thoughts above about this possibly reflecting the blocking efforts of the WRs and TEs. Perhaps the Bears missed Trey Burton, Taylor Gabriel, and Josh Bellamy blocking on the edges more than we realized.

Closing Thoughts

So far, the data says that David Montgomery in 2019 was used in a very similar manner to Jordan Howard in 2018, and Tarik Cohen’s usage didn’t change all that much either. What did change was their efficiency, especially outside the tackles.

So maybe Chicago’s run blocking wasn’t actually that much worse in 2019 than 2018, especially from the offensive line. Instead, Mitchell Trubisky stopped utilizing his running ability, and his passing difficulties shined a glare on the run game, which has struggled since Matt Nagy showed up.

In my next article, coming tomorrow, I’ll look at rushing success rates, which I mentioned in the intro but have otherwise ignored in this piece. They’re a different way of evaluating the running game, and exploring them will provide some interesting context into how injuries to the right side of Chicago’s offensive line contributed to their running game woes.

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