In an earlier post, we looked at 45 active NFL quarterbacks to understand which QBs have more good games than others. Our 45-QB sample showed that in games in which those 45 QBs started, had at least 10 pass attempts, and posted a QBR of 75 or higher, they were a combined 717-164-2 for a win percentage of .812

But if you want to be a top QB in this league, it’s not enough to have a bunch of 75+ QBR games that give your team a good chance to win. It’s at least equally important to minimize the number of bad games in which QBs actively lose games for their teams.

If we look at the games in our sample with a Total QBR below 40, those 45 QBs combined for a 218-625-4 record, a measly .257 win percentage, or about 25 percent.

It follows that if a Total QBR above 75 is a good game, a Total QBR below 40 is a bad game.

So here’s the same exercise as in the previous post, except with games with a QBR below 40. We’ll start off with the 36 QBs with more than 20 starts again, though this time a low “bad-game percentage” is what you are looking for.

This list is utterly dominated by Patrick Mahomes. Incredibly, he’s only averaging about one “bad game” per season. Compare that to some random QB like Eli Manning, whose 38.8 bad game percentage would be the equivalent of seven bad games per 17-game season. Relative to his peers, Mahomes is truly on a different planet.

The second tier here are QBs that simply don’t have a lot of stinkers on their ledger, which means their performance very rarely is the reason their team loses. That does not automatically make them elite QBs, but the numbers here suggest they minimize their errors and bad plays and consistently keep their teams in the game, losing efforts notwithstanding. The interesting thing here is there seems to be a new guard (Drake Maye, Jordan Love, Brock Purdy) here complementing the old guard (Matthew Stafford, Josh Allen, Dak Prescott, Lamar Jackson) of high-performing QB.

The third tier consists of a bevy of well-known names like Justin Herbert, Joe Burrow, Kyler Murray, Jalen Hurts, and Kirk Cousins, who are averaging around 3.5 to 4.5 “bad games” per 17-game season. Still above average (the 45-QB average is 26.7%, or 4.5 games), but not quite at the level of the top guys.

The fourth tier is a collection of below-average performers, who deliver between 4.6 and 6.5 “bad games” per year.

The final tier finds us in the Eli Manning pit of endless misery where guys are averaging about seven bad games per year.

One thing of note here are the W/L records in these bad games. Guys like Dak Prescott (5-21 in sub-40 QBR games), Matthew Stafford (2-24), or Drew Brees (3-11) have really bad win percentages in these games. Others, like Jalen Hurts (10-10), Lamar Jackson (13-7), or Tom Brady (11-13) have much better win percentages, which suggests their teams are better able to overcome a bad day by the QB, whereas the QBs in the first group seem to play on teams that are unable to bail them out on a bad day.

Here’s a highlight table of key QBs benefiting the most or least from their teams bailing them out on a bad day (QBR < 40).

On to the players with less than 20 starts, same procedure as above.

The surprise here, at least for me, is Jaxson Dart. In the previous post, we had called him a Daniel Jones/Eli Manning clone for his sub-par “good game percentage” of just 16.7%. And while Dart doesn’t have a lot of 75+ QBR games, he also doesn’t have a lot of <40 QBR games, so he doesn’t lose his team too many games. And that’s not something we were able to say about Jones or Manning.

And Tyler Shough has the same logic going for him. Didn’t have a lot of 75+ QBR games, but at least he’s not losing too many games for the Saints.

As for the rest of the list, hard to see a lot of upside there.

In principle, you want a QB who doesn’t cost you too many games (and ideally wins a few games for you too). Posting a QBR below 40 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.

But to be a top QB in the league need both: a high number of 75+ QBR games that give your team a good chance to win and a low number of <40 QBR games that significantly increase your odds of losing.

Over 138 games (with min 10 pass attempts), Dak Prescott had 53 games with a 75+ QBR. Only four of his active peers have a better good-game percentage. And he’s had just 26 sub-40 QBR games. Only six of his peers have a lower bad-game percentage.

Over the last 10 years, Prescott has a record of 42-10-1 (.750) in his 53 games with a QBR above 75. For comparison, Lamar Jackson has a 35-4 record (.897) in such games, thanks in in large part to a better supporting cast in Baltimore. Similarly, Prescott is 5-21 (.192) in games with a QBR below 40, where Jackson is 13-7 (.650).

Applying Jackson’s win percentages to Prescott’s record in these game would improve it from 47-31-1 to 64-15, a 17-win swing, or an average of close to two extra wins per season over the last 10 years. That’s what the front office could have gotten out of Prescott with a better supporting cast, better coaching, and better talent acquisition.

Ultimately, it’s not one player that wins and loses games. Dak Prescott has more than his fair share of detractors, and even more so among Cowboys fans it seems. But if you judge a QB by the statistical company he keeps, Dak Prescott is at the very top of the game.