QB WAR (Wins Above Replacement)

Overview

This pillar quantifies the point spread value of a starting quarterback compared to their backup. It's essential for reacting to injury news or potential benchings, which cause the largest line movements in the NFL.

What It Does

QB WAR analyzes historical performance data for both the starting QB and their backup, focusing on efficiency metrics like EPA per play. It then translates the performance gap into a concrete point spread value. This calculation provides an objective measure of how many points a specific quarterback is worth to their team's trading line.

Why It Matters

The market often overreacts or underreacts to quarterback news. This pillar provides a data-driven anchor point, allowing you to assess if a new betting line is accurate or presents a valuable opportunity before the public catches on.

How It Works

First, the model gathers historical performance data for the starter and backup, weighting recent games more heavily. It then calculates the differential in key efficiency stats like EPA and CPOE. Finally, this differential is fed into a regression model that converts the performance gap into an estimated point spread adjustment.

Methodology

The pillar calculates a QB's spread value by comparing their 3-year rolling average for Expected Points Added (EPA) per play and Completion Percentage Over Expectation (CPOE) against their backup's historical data. The differential is then input into a regression model trained on over a decade of NFL data, which correlates performance gaps to final score differences. The model adjusts for opponent strength and gives a higher weight to more recent seasons.

Edge & Advantage

It provides a precise, data-backed number for spread adjustments instantly when QB news breaks, beating the market's often slow or emotional reactions.

Key Indicators

• Spread Delta

  high

  The final calculated point spread difference between the starting QB and their backup.

• Backup QB Historical EPA

  high

  The backup's career Expected Points Added per play, indicating their baseline performance level.

• Dropback Efficiency Diff

  medium

  The difference in a composite efficiency score (EPA+CPOE) between the two quarterbacks on passing plays.

Data Sources

• nflfastR / nfl-data-py

  Provides historical NFL play-by-play data used to calculate EPA and CPOE.

• Pro Football Focus (PFF)

  Offers player grades and advanced statistics that supplement play-by-play data.

• Sportsbook Odds APIs

  Provides historical betting lines used to train and validate the spread impact model.

Example Questions This Pillar Answers

• → What will the point spread for the 49ers vs. Rams game be if the starting QB is ruled out?
• → Will the betting line for the Chiefs vs. Broncos game move by more than 6 points if the starting QB is injured?
• → Will Team A cover the spread against Team B with their backup quarterback starting?

Tags