Stacking the Box Score: Patrick Mahomes is NFL’s best quarterback when trailing

Welcome to this week’s Stacking the Box Score, where I’ll be quantifying what went down between the Kansas City Chiefs in their most recent game.

As always, here’s a quick primer on some of the stats and data I’ll be using. If you already feel comfortable with these metrics, skip the link and keep reading!

Chiefs vs. Houston Texans, January 12th

Win probability

In order to spend more time on the meat of this article (which we’ll get to in a minute), I’m borrowing an animated win probability chart from my friend Lee Sharpe (who you should definitely follow on twitter if you’re looking for more NFL analytics content @LeeSharpeNFL).

A couple of quick things to point out here. One, the Chief’s blocked punt actually wasn’t as damaging as many fans may have believed. The Chiefs were giving the ball back to the Texans regardless, so it’s just a matter of field position (though don’t get me wrong — it certainly didn’t help). And two, the win probability model gave the Texans a 99% chance to win the game at one point in the first quarter. The beginning of their downward slide? A made field goal by the Texans. Failing to go for the fourth-and-inches actually hurt their chances of winning the game, from which they never recovered.

Why not?

Patrick. Lavon. Mahomes. II.

There are a lot of things I wanted to emphasize when I set out to write this article. Travis Kelce absolutely dominated (on a gimp knee and hamstring, no less), posting the highest total Expected Points Added (EPA) of his career. Andy Reid kept the pedal to the metal, continuing to stay aggressive and dial up passes late into the game.

But nothing stuck out to me more than the brilliant, resilient performance by Patrick Mahomes. This game was perfect for Mahomes. From a stats level, it was other-worldly: he had the third-best game of his career by EPA per drop back (the first was the Steelers game in 2018, the second was against Jacksonville in Week 1 this season). It’s also the fifth-best performance by a quarterback in the postseason since 2009, where our dataset begins. And, that doesn’t take into account his four drops - without those, his EPA would have undoubtedly been higher than any game in his career.

Perhaps most astoundingly, though, is how impressive he played with his back against the wall. This has been a theme for Mahomes — there’s a reason not a single Chiefs loss since 2018 has been decided by more than a touchdown. No matter what the situation, no matter how the Chiefs found themselves in a hole, he is there to bring them right back into it. Let’s dig into our advanced stats to find evidence for this narrative.

Another week, another Mahomes chart that makes me go, “wow.” There’s a lot going on in this chart, so let me break it down for you. What I’ve done is grouped all the dropbacks from all quarterbacks in the league into five buckets based on their win probability at the time of the play (0-20%, 20-40%, 40-60%, 60-80%, 80-100%). This is a technique known as binning. I’ve then averaged the EPA of all of the dropbacks within each category — these are represented by the dots plotted above, with a smoothed line connecting them.

If we focus on the black dotted line, we see that the NFL average quarterback is slightly worse when heavily trailing than with a lead. But, we already know Mahomes is far better than the average quarterback — so, I compared him to some of the league’s other top quarterbacks as well.

The results are staggering. With under a 20% chance of winning the game, Mahomes averages 27x higher EPA per drop back than the average drop back in this scenario, and over double the league’s closest competitor, Green Bay quarterback Aaron Rodgers. And he’s got over 60 attempts in this category, so this isn’t just a tiny sample size effect.

Let’s do this same analysis one more time, but with Win Probability Added. Only, this time we’ll add a twist. We’ll again bin and average the quarterback’s dropbacks by win probability at the time of the drop back, only this time we’ll divide this number by the difference between the current win probability and 50% (tying up the game). This will give us the average number of dropbacks necessary for that quarterback to complete a comeback at each win probability. In other words, if Mahomes has a 10% chance to win the game by our model, how many times must the Chiefs pass the ball for that to be 50%?

Again - this is staggering. When given anywhere from a 0-20% chance at winning the game, Mahomes only needs 20 dropbacks to complete the comeback. The next lowest quarterback is Russell Wilson at around 50, while the NFL average is around 115. Lamar Jackson was removed from this chart as he needed 300 dropbacks to complete the comeback, breaking the scale of the chart.

We know Mahomes is the best quarterback in the NFL. But there are honestly no words to describe how good he’s been with his back against the wall. He’s been better than every quarterback to grace the football field since 2009, and it isn’t even close.

A lot of bad luck can befall a team. They can have four drops, a blocked punt, and then a muffed return. But Chiefs fans can be comforted knowing they’ll always be in it with Mahomes at the helm.