Which teams got it right on fourth-down and 2-point conversion calls in Week 5 of the 2021 NFL season -- and which teams got it wrong? The Next Gen Stats analytics team uses the Next Gen Stats Decision Guide powered by AWS to break down the numbers behind the decisions that shaped the game.
Brandon Staley and Kevin Stefanski call a "perfect game"
In a shootout where both teams combined for 89 points -- the most in a game this season -- finding the end zone instead of settling for field goals was paramount to keeping up. Both the Chargers' Staley and the Browns' Stefanski understood the situation (and the numbers) and correctly went for it on fourth down a combined eight times (four each). The NGS Decision Guide was in alignment in every situation. Over the course of the game, the two teams combined for 16 fourth-down calls, 13 of which came with a recommendation that affected the team's chances of winning by more than 1 percent. Staley (five) and Stefanski (eight) got all 13 decisions correct. Staley even went for 2 down eight late in the third quarter -- and the numbers agreed with that decision, too.
FOURTH QUARTER: With 9:10 remaining and the Chargers (trailing 35-28) facing a fourth-and-4 from their own 41-yard line, Mike Williams draws a defensive pass-interference penalty; the Chargers are awarded with a 33-yard gain and a new set of downs.
The Chargers went for it on fourth down four times in the second half, converting for a first down in all four situations. And perhaps no play was more critical to Los Angeles' ability to get back in the game after falling behind than this one.
The Guide said converting here would have increased the Chargers' chances of winning from 18 percent to 25 percent. If they failed, their chances of winning would have dropped to 11 percent. If they punted, their chances of winning would have dropped to 15 percent. Taking into account the odds of converting a first down (48 percent), the NGS Decision Guide recommended the Chargers go for it by an advantage of 3.1 percentage points in expected win probability value. The resulting pass-interference penalty actually jumped their win probability to 33 percent.
To effectively evaluate a team's chances of converting on fourth down, the math takes into account more than just the odds of gaining the necessary yards through the air or on the ground -- the formula also has to account for penalties. When you have one of the top 50-50 ball receivers in the NFL in Mike Williams, your chances of converting are even higher than the probability of a completion, given the increased likelihood of Williams inducing a defensive pass-interference call.
Staley and Co. have been rewarded for their wisely aggressive approach so far this season. The Chargers have converted for a first down on seven of their eight fourth-down attempts in 2021. The offense's conversion rate of 87.5 percent ranks third in the NFL, behind only the Cardinals (3-of-3, 100%) and Broncos (8-of-9, 88.9%).
Staley was not the only coach in the game to get it right on fourth down ...
The Browns had a chance to tie the game going into halftime with a field goal -- or take the lead if they converted. And 2020's strongest decision-maker (per the NGS Decision Guide) decided to go with a move that, per the Guide, would have increased their chances of winning by 5.5 percentage points.
According to our ball-tracking data, the Browns needed approximately 0.7 yards to gain a first down and 2.8 yards for a touchdown. Their chances of converting in this situation -- 68 percent -- takes into account their chances of converting if they run or pass. But that number increases to 79 percent if they call a run play ... which they did, resulting in the 3-yard score. Following a costly fumble by Austin Ekeler on the Chargers' next drive, the Browns were able to add a field goal to their advantage and entered halftime with a 73 percent chance to win the game.
The Browns' win probability climbed as high as 89 percent midway through the third quarter and sat at 86 percent with four minutes left in the game. But Staley countered with his own analytically-driven aggressiveness, and Justin Herbert and the Chargers' offense pulled off the comeback and secured a 4-1 start to the season.
Sean Payton plays it smart on his side of the field
For the third consecutive week, we highlight a coach making the right decision to go for it in a fourth-and-short situation in their own territory:
FOURTH QUARTER: With 6:12 remaining and the Saints (leading 27-22) facing a fourth-and-1 from their own 34-yard line, Jameis Winston gains 2 yards on a QB sneak, securing a first down.
With New Orleans protecting a slim advantage, many likely would have been tempted to punt the ball away and prevent Washington from moving into an easy position to take the lead. Instead, Payton decided to try to keep the drive alive.
Our ball-tracking data reveals that the Saints were just 0.5 yards away from the first-down markers, and at such a short distance, they had a 72 percent chance of picking up the first down. Facing that high conversion probability, Payton decided to trust his offense to pick up the first down. The NGS Decision Guide strongly supported Payton’s actions, finding that going for it was the optimal call by 5.2 percentage points in expected win probability.
After the successful conversion, the Saints' win probability rose to 88 percent. They would go on to score a touchdown four plays later, all but putting this game out of reach.
Zac Taylor pays for late field-goal call
A week ago, we outlined the suboptimal decision made by Patriots coach Bill Belichick to kick a 56-yard field goal in the final minutes of a close game, leaving too much time on the clock for a future Hall of Fame quarterback to work with. This week, Taylor followed Belichick’s conservative path while facing a similar decision -- and the call resulted in a massive loss of win probability value for the Bengals (13.1 percentage points).
FOURTH QUARTER: With 26 seconds remaining and the Bengals (tied 22-22) facing a fourth-and-2 from the Packers' 39-yard line, Cincinnati's Evan McPherson misses a 57-yard field-goal attempt.
Our model pegged a successful first-down conversion to be significantly more likely than a successful field-goal attempt, driving the hefty recommendation to go for it. McPherson had a 40 percent chance to make the 57-yard field-goal attempt. On the other hand, the Bengals' offense had a 63 percent probability to gain the 2 yards necessary for the first down.
One does not need to be an analytics expert to see the huge difference between these conversion probabilities. Instead, McPherson missed the kick and Cincinnati went on to lose in overtime.