In San Francisco, Shanahan Will Inherit Third-Worst Run Defense In NFL History
While the departed Chip Kelly and the 49ers’ offense deserve at least some of the blame, fixing things may be a challenge.
Nearly four years ago, the San Francisco 49ers came a few yards short of a Lombardi Trophy. Today, it is a franchise in disarray, fresh off a 2–14 season, second-worst in the NFL. The team has an unpopular $1.3 billion stadium, unwanted ownership, and an unhappy fan base. They will soon experience life under a first-time head coach, Kyle Shanahan, and a general manager, John Lynch, who comes in with no front-office experience.
Considered an “offensive guru” and rising star in the NFL’s coaching ranks, Shanahan inherits the second-worst offense and single-worst defense in the league. Much was made of that defense throughout the season, especially when it allowed a record seven-straight 100-yard rushers, but it’s worth a taking deeper look at how historically bad San Francisco’s rushing defense was.
In allowing 166 rushing yards per game to opposing teams, the 2016 49ers finished with the 106th-worst yards-per-game-against mark of 1,929 teams since 1933. That’s fifth-percentile bad and sixth-worst since 1990 — pretty bad, but probably not worth a whole story.
(1933 is the earliest season for which pro-football-reference publishes opponents’ rushing statistics. This analysis includes the American Football League (1960–1969) and All America Football Conference (1946–1949). References to “league history” or “NFL history” include these leagues.)
What makes those marks special is the fact that the Niners compiled them in an era when teams don’t run the ball all that much. 2016 had the fewest rushing attempts (26) and sixth-fewest rushing yards per team game (109) since 1933. Viewed in seasonal context — that is, measured relative to league rushing yards-against averages in terms of standard deviations — the 2016 49ers had the third-worst run defense of all-time.
The 166 rushing yards per game San Francisco allowed last season was 3.04 standard deviations above the league’s 109-yard average. Only the 1999 Browns (2–14) and 1980 Saints (1–15) were worse against the run relative to the rest of the league in the seasons they played.
As always, historical feats (of excellence, ineptitude, or happenstance) require a special combination of circumstances. Last season, the 49ers bequeathed 4.8 yards per carry to opposing rushers — 56th worst all-time in absolute terms and 80th-worst relative to 2016’s 4.2-yard average (1.7 standard deviations above the mean).
The 49ers’ 34.3 rush attempts against per game are nothing to write home about in absolute terms — they’re on par with league averages in parts of the run-heavy 1950s and 1970s and rank only 448th all-time. But that mark was 32 percent more than the typical team today (3.0 standard deviations above the mean) — the second-biggest outlier in NFL history.
Key to that “special combination” was the Niners (now-former) head coach, Chip Kelly. Famous for his up-tempo offense — and perhaps now infamous for his conviction that ball control doesn’t matter — Kelly guided his Philadelphia Eagles (2013–2015) and Niners (2016) to the fastest offensive pace and lowest time of possession in all four seasons he coached in the pros.
Kelly’s 2013 and 2014 Eagles played fast and scored points (both went 10–6), but the Chip Kelly Experiment featured a mediocre offense in Philadelphia in 2015 and a terrible one in San Francisco in 2016. Without leads or the ball, the 2015 Eagles and 2016 Niners were punished on the ground. Both finished last in the NFL in rushes against and rushing yards allowed. In this way, the 2016 49ers run defense was horrific in part because its offense played fast and sucked.
(Even without any personnel changes on defense, the San Francisco run defense should allow fewer yards per game going forward if the offense improves and/or holds the ball more, which seems likely under Shanahan.)
Under Jim Harbaugh, the 2011 49ers were 13th-best in NFL history in rushing yards per game allowed relative to league average, putting them above the 99th percentile all-time (among 1,929 teams since 1933). Five years later — and four years after that Super Bowl appearance — the Niners run defense is among the worst that ever played.
To think how far they’ve fallen. And to think how close they came.
Originally published at www.eldo.co.
