• John Bulmer

Gimme a Break: Why an Elite QB Will Improve the 49ers’ Defense

Image Credit: Associated Press


OK, so this makes perfect sense - right? I mean, its perceived wisdom, everybody knows it; defenses get gassed if they are on the field too long.The extra gear worn by NFL players weighs up to 10 pounds; imagine being 250 pounds plus and charging around in that - right? Football is a fast, violent sport with regular high speed collisions, so it must take a toll? That’s pretty much what I thought before researching this article but sometimes all is not what it seems.

What the Research Tell Us

Football Outsiders did a piece of research on this very question in 2011 in which Daniel Lawver proved no direct relationship between defensive DVOA over the course of a season and a team’s average offensive plays per drive.

The same website then produced a follow up research piece in 2018, written by Ben Baldwin, where he aimed to revisit this idea and look at the relationship between defensive rest and performance. It is a very well researched piece with what seems like a very solid and well-reasoned methodology and I would recommend readers to seek it out for further details.

The Cliff’s Notes version though is this: Long drives (high number of plays) does not lead to the defense performing better on the subsequent drive; neither does chewing up lots of clock. Similarly, he posited that running lots of plays against a defense does not make it easier to score against them as the game progresses and neither does having a high time of possession.

In 2020, the San Francisco 49ers ranked sixth in the NFL in time of possession, a major improvement from 2016 (before the Shanahan-Lynch era started) when they were dead last. Part of the reason for this is that Kyle has implemented an offense which prioritizes running the ball. However, in spite of this, they ranked a very mediocre seventeenth in the league in points allowed per game which seems to tally with the research I mentioned earlier.

So How Can Elite Quarterback Play Help the Defense?

Well, one thing did become clear from this piece of research: the key is not time of possession, but starting field position.

If the 49ers can improve their quarterback play, reduce the number of three-and-outs and turnovers, then they can give their defense a longer field to defend and a much better chance. This is where a higher level of quarterback play comes in, and where it can help the defense. Last season, due to Jimmy Garoppolo’s injury and the inconsistent (I’m being generous!) play from Nick Mullens and C.J. Beathard, the 49ers were frequently giving the opposition a good starting position, putting the defense under duress straight away.

So yes, elite quarterback play also benefits the defense but not necessarily in the way that you might think. Extending drives and converting on third down allows your offense to advance up the field and gives the defense a longer field to defend and a better chance of keeping the opposition out of the end zone.

An athletic quarterback helps even more in this regard because of the flexibility he allows in play calling. It’s much trickier to defend deep and rush with four in third-and-long situations when you know that the opposition quarterback can run a 4.4 40-time and can make the difference by getting outside the rush and using his legs. A Fields or Lance would give that kind of option and quickly become not only the darling of the fans but also the defense’s best friend.


The 49ers have ranked between twentieth and thirtieth in the league for interceptions per game during Kyle’s reign which is clearly not good enough. In spite of this, the defense has held up well, allowing them to remain competitive.

All three quarterbacks linked to the 49ers in the draft would hope to reduce the number of turnovers to a more acceptable level, thereby helping out the defense by not giving the opposition a chance to play on a short field. For their college careers, Mac Jones had seven interceptions in 556 attempts, Justin Fields had nine from 618 attempts, and Trey Lance had zero interceptions from 288 attempts.

By way of contrast, Jimmy Garoppolo has 26 interceptions from 977 career attempts (2.66 percent), more than double that of Mac Jones and much higher than Justin Fields and Trey Lance. Obviously, it is difficult to compare college stats to the much higher level of the NFL but what it does show is that all three of the contenders seem to know how to look after the football.


Although the studies seem to show little statistical basis for elite quarterback play benefitting the defense, we’ve all seen games when our eyes seem to be telling a different story. A reduced snap count for the defense also should help to reduce wear and tear, thereby cutting the number of injuries suffered to key defensive personnel.

In my opinion, I think that the benefits of an upgrade at quarterback will be felt right across the team and the one intangible we haven’t discussed is the lowering of pressure on the defense. Knowing that you don’t have to be perfect, don’t have to carry the team as they have in the last year will certainly be a massive psychological boost and this lowering of mental stress could also reap huge benefits.

The aphorism “A rising tide lifts all boats” comes to mind.


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