The 2023 NFL season has reached its essential quarter mark, so what better time to assess the performance of the league’s quarterbacks? However, rather than an overall evaluation of quarterback play, we’re going to focus solely on the game’s most important moments and use The Athletic’s Quarterback Reliability Index (QRI) to rank the NFL’s current primary starters in those situations.
The QRI is a model that measures quarterback performance in high-leverage situations as a way to quantify the level to which a team relies on that player’s ability when it matters most. These high-level situations include third- and fourth-down plays and late-game sequences all while filtering out plays in which the in-game win probability is greater than 80% for either team. In other words, when the game is on the line, this metric attempts to evaluate how well a quarterback has gotten the job done.
Passing- and rushing-related metrics within the model include versions of expected points added (EPA), success rate (play with a positive EPA is considered a successful play), and win probability added (WPA). Using the metrics, the model calculates a rating similar to Wins Above Replacement (WAR) in baseball. The rating represents how many wins better the given QB has been than a replacement-level QB in the aforementioned high-leverage situations.
For a more thorough evaluation, the index includes data from all games since the start of the 2022 season (for applicable players) with recent games weighted more heavily. Until more games are played, rookies and newer starters have smaller sample sizes and will be more susceptible to bigger swings. We’re solely including this season’s primary starting quarterbacks for a cleaner 1-to-32 ranking.
NFL QB Reliability Index – Thru Week 4
Rookie (only 2023 stats included)
Why is 49ers QB Brock Purdy No. 1 in the QRI?
Brock Purdy has been exceptional in just about every metric and situation, ranking at or near the top in various forms of EPA, success rate, and WPA. Purdy also performed well on third and fourth downs as well as when the game was on the line in the fourth quarter. It’s no surprise that he’s undefeated as a starter in his regular season career and seems to lead the 49ers offense to 30-point games every time out. — Austin Mock, NFL staff writer
What has made Purdy so successful in high-leverage situations?
There’s obviously a comfort level present between 49ers coach Kyle Shanahan and Purdy that’s atypical when it comes to playcaller-young QB relationships. It dates back to Purdy’s first action after taking over for the injured Jimmy Garoppolo against the Miami Dolphins last season. Purdy calmly stared down the barrel of numerous Miami blitzes and delivered downfield. He then further earned Shanahan’s trust by playing a gritty game with a broken rib at Seattle. This season, Shanahan has given Purdy the reins on two key fourth-down situations. One, on the first drive of the opener, seems to have set the tone for the season: In the Pittsburgh din, Purdy calmly hit George Kittle to move the chains. — David Lombardi, 49ers beat writer
Why is Jimmy Garoppolo ranked so high in the QRI?
Garoppolo’s success in San Francisco when healthy last season boosts his metrics considerably. Kyle Shanahan and the roster that the 49ers have built is perfect for a quarterback like Jimmy G (and Purdy). They’re guys who can get the ball out on time and with accuracy, which allows their elite skill players to make plays. Garoppolo hasn’t been as effective in his Raiders tenure to date. If that continues, his ranking will fall as we gather more data. — Austin Mock, NFL staff writer
In conclusion, the Quarterback Reliability Index (QRI) provides a unique perspective on the performance of NFL quarterbacks in high-leverage situations. It takes into account various metrics such as expected points added, success rate, and win probability added to determine a quarterback’s rating in these critical moments. Currently, Brock Purdy of the San Francisco 49ers holds the top spot in the QRI, showcasing his exceptional performance and ability to deliver when it matters most. However, it’s important to note that the rankings are based on a limited sample size, and as more games are played, the rankings may shift. Nonetheless, the QRI offers valuable insights into the reliability and effectiveness of quarterbacks in crucial game situations.