Ranking NFL quarterbacks by their number of bad games per season

oEarlier this week, in a post titled “Ranking NFL QBs by their 100+ passer rating games”, we took a look at the number of games in which currently active NFL QBs recorded a passer rating of 100 or more, compared their W/L records in those games and looked at their 100+ rating games as a percentage of games started.

What we found was that some QBs get a lot more help from their teams when they have a good game than others do, a reflection of the fact that it’s not just one single player that wins and loses games.

We also saw that Dak Prescott looked a lot better than many expected, while other QBs looked worse than many expected, prompting questions about whether the stats had been cherry-picked to make Prescott look good. So today, as promised in the original article, we’re going to turn things around and look at poor QB performances to see which teams bail out their QBs when they have a bad game.

But how can we define a “bad game?”

When the NFL passer rating (not to be confused with ESPN’s QBR) was initially developed in 1973, the objective was to create a single number that would differentiate between outstanding, excellent, average, and poor performance. Below are the metrics the developers of the formula felt best denoted those performances at the time, and which they combined into the passer rating we know and use today.

When the passer rating was initially developed, a passer rating of 66.7 was considered average, and everything below that was obviously below average. In 1973, 61.7 was the average passer rating in the NFL. A little over 40 years later, the NFL average has improved significantly. In 2017, the NFL average passer rating was 85.1. For the purposes of this post, we’ll stick to the 66.7 passer rating from the original formula, except we won’t consider it an average or below average performance, we’ll call it what it is: a poor performance, perhaps even a stinker, but certainly a “bad game”.

Here are three examples of what such a “bad game” can look like for a QB. The first is Dak Prescott's stat line from the 6-28 loss to the Chargers last year. The second is a Tom Brady loss in Miami, the third is a Matt Ryan loss against Buffalo, both from last year as well.

The numbers illustrate that by today’s standards, anything below 66.7 is a really poor game by the QB (and it also shows that even some of the best NFL QBs have the occasional stinker of a game). Another reason why 66.7 denotes a poor performance is the W/L record of QBs in such games. Pro-Football-Reference.com shows that there were 81 nominally active QBs in the NFL in 2017 who have thrown for less than a 66.7 passer rating at least once in their career. The combined W/L record of those QBs in such games is 193-797-1 for a decidedly unimpressive .195 winning percentage.

To find out which of the QBs in the league have stunk it up the most, we’ll first look at the 39 active NFL QBs who’ve started more than 28 games in their career and look at some of their metrics in sub 66.7 games. Minor note on the data I’m using: All QB data here is from games in which the QB started, and in which he had at least five completions. This avoids penalizing guys who may have come in late in the game and removes games in which the starter had to leave early, usually due to an injury.

Follow the Pro-Football-Reference link provided above if you want to play around with the base data. For example, you could include all QBs between 2001 and 2017, not just the currently active QBs; you could include playoff games if you wanted to; you could put in a filter for the minimum amount of pass attempts needed to qualify; you can do whatever you want, but for now you’re stuck with the parameters I defined.

With that out of the way, here’s the data neatly laid out in a sortable table:

Bad Games (click on column headers to sort)

At first glance, this table doesn’t tell you much more than “some guys have more bad games than others.” And while this is without a doubt a universally applicable truth, there are a lot more interesting details to be found in the table.

Percentage of bad games

The table is pre-sorted by the total number of “bad games”, which makes this one of the few QB rankings that has Eli Manning at the top: Over his career, he has thrown more bad games than any other QB in this millennium.

If you sort the table by the column titled “Bad Games in %”, you'll to see the quarterbacks with the lowest percentage of poor games at the top of the table. At the very top of the rankings you’ll find Aaron Rodgers, who was also the leader in the earlier post on percentage of good games. Number of rings notwithstanding, Aaron Rodgers is probably the best QB in the league.

In 142 games as a starter over 10 seasons, he’s only had 12 games with a passer rating below 66.7, a “bad game” percentage of just 8%. Think about that for a minute. Rodgers leads all QBs with the highest percentage “good games”, and also leads the league in the lowest number of “bad games.” That is phenomenal.

Rodgers is followed closely by five QBs who are all tightly bunched between a 10% and 13% bad game percentage: Tom Brady, Russell Wilson, Kirk Cousins, Drew Brees, and Matt Ryan make up the first tier of QBs after Rodgers. It's probably not a coincidence that the top six guys in “bad game percentage” all rank within the top eight in “good game percentage” as well.

The top six QBs are followed by a second tier of nine more QBs who all have a bad game percentage between 14% and 19% (Rivers, Roethlisberger, Taylor, Mariota, Wentz, Schaub, Carr, Stafford, Prescott) and this second tier closes out the list of the top QBs in the league with a bad game percentage below 20%.

Average number of bad games per season

Another way of looking at these numbers that makes them perhaps a little more intuitive is to translate them into average bad games per season. In Aaron Rodgers’ case 8% of a 16-game regular season is 1.4 bad games per season.

Even the best QBs in the NFL average around two bad games per season. So the next time you hear a derogatory comment about a QB who is “always good for two or three bad games per season”, take that as a compliment. Because two or three bad games rival the very best QBs in the league, and are a lot better than guys like Cam Newton (4.0), Eli Manning (4.3), or Blake Bortles (5.2).

Which brings us neatly to the next topic, the W/L record of QBs in games with a passer rating below 66.7:

How teams bail out their QBs on a bad day

The last column in the table above shows the win percentage of QBs in sub 66.7 games. If you sort the table by win percentage, the first thing you may notice is that there’s an incredible spread of winning percentages. The Raiders have never won a game in which Derek Carr had a passer rating below 66.7, thus Carr’s .000 win percentage.

At the other end of the spectrum, you’ve got Teddy Bridgewater (.571) and Matt Ryan (.450) with ridiculously high winning percentages, considering that both QBs delivered dirt-poor performances as a passer in those games. Of note, Matt Ryan also had one of the highest winning percentages in games in which he had a 100+ passer rating. Combined, these two numbers indicate that the rest of the Falcons have a significant positive effect on Matt Ryan’s 95-63 career record.

Let’s do a little Matt Ryan math

The average winning percentage in sub 66.7 games is .195. Applying that to Ryan’s 20 sub 66.7 games would result in a 4-16 W/L record instead of Ryan’s actual 9-11 record. Similarly, applying the league average win percentage of .792 in 100+ rating games to Ryan’s 57-10 record in 100+ rating games would yield only a 53-14 record. In total, that’s a swing of nine games in Ryan’s favor. With league average win percentages, Ryan would have an “adjusted” W/L record of 86-72 instead of his actual 95-63 record, and his career win percentage would drop from .601 to .544, a swing of .057 percentage points,

In other words, Matt Ryan’s record is better than it would be if he were on an average team. It’s only because the rest of the Falcons are adept at bailing him out on a bad day, and riding him on a good day that his record is what it is. Which just goes to show that it’s not one player that wins and loses games.

The next table shows what that Matt-Ryan-math looks like for all 39 QBs we're looking at today. The QBs on the left (green) have a career W/L that is better than what their adjusted W/L record is, which means they likely have had a better supporting cast around them than an average QB. The QBs on the right (red) have a career W/L that is worse than their adjusted W/L, suggesting that they have played on some bad teams that weren't able to bail out their QB on occasion.

Going by the win percentages in the table above, the QBs who've had the best supporting casts include Tom Brady, Dak Prescott, Cam Newton, Matt Ryan, Russell Wilson, and Ben Roethlisberger.

For Cowboys fans, Prescott's ranking is good news (even if we're dealing with small sample sizes here). Here's why: using the same Matt Ryan Math on Tony Romo shows that Romo's Adjusted W/L should be 81-46 instead of the actual 78-49, a swing of -.022, which would place Romo just ahead of Geno Smith on the right side of the table above. This suggests that Romo has been playing with an average supporting cast his whole career, while Prescott may have a supporting cast on the level the Patriots, Panthers, Falcons, Seahawks, and Steelers have. That's a very good peer group to be in.

Dak Prescott

We know from my earlier article that Prescott has the second-highest percentage of 100+ rating games in the league behind only Aaron Rodgers. His “bad game percentage” of 19% ranks a much less impressive 14th in the league and highlights a key area of improvement for Prescott: consistency.

As an aspiring top QB, it's not enough to have a bunch of 100+ passer rating games that give your team a good chance to win. It's at least equally important to minimize your number of bad games in which QBs actively lose games for their team.

Over his first 24 games, Prescott had 15 100+ rating games and just two sub 66.7 games. In his last eight games, that ratio flipped to 1-4. That's got to get better before Prescott can firmly establish himself as a top QB in the league.

In principle, you want a QB who doesn’t cost you too many games (and ideally wins a few games with his arm too). Throwing for a passer rating below 66.7 is a good way to lose games, even if you have a team that can bail you out on occasion with a good running game, a strong defense, or a big-play special teams unit.

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I didn’t include some of the younger QBs in the table above, because I felt that the small sample size (less than 28 starts) could possibly distort the overall picture. But for completeness’ sake, here are 21 additional QBs who’ve had between 6 and 25 starts in their NFL careers so far.

Bad Games by young QBs (click on column headers to sort)

We probably need to reserve judgment on some of the guys on this list until they play more games and we have a more robust sample size to look at, so we shouldn’t place too much weight on their numbers right now. But once more than a quarter of your games are stinkers, you’ve got to wonder about how good those guys really are.

Then again, Eli Manning has a bad game percentage of 27% and plenty of people think he’s a good QB, so there’s always that.

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If you thought this post has a familiar feel to it, you’re right. I originally published a look at bad game percentages back in 2013, and my good friend KD Drummond recently reminded me about that post, so I went ahead and updated the data five years later.