Analyzing the Offensive Line’s Effect on QB Performance (Fantasy Football)

Introduction

If you haven’t read the first edition of this article series, which takes a look at O-line’s effect on RB performance, check it out here. In fantasy football, the performance of quarterbacks is meticulously analyzed to gain an edge in making winning picks. In the NFL, a strong offensive line can provide essential protection, giving quarterbacks the time needed to make accurate throws and avoid sacks, while a weak one could force QBs into poor decisions, leading to incompletions and interceptions. This article will investigate how big an impact offensive lines have on the fantasy football performance of quarterbacks.

Approach

To investigate the extent of an O-line’s impact on quarterbacks, I first needed a way to ‘grade’ O-lines. To do this, I gathered a number of important offensive line metrics for each team, which included average time to throw (weighted by number of rushers), pressure percent, average expected rush yards, average time to line of scrimmage (run plays), average yards until contact (run plays), and expected fantasy rush points per game. Following this, I put together a simple multi-linear regression model to see which metrics were the most important in predicting fantasy pass points per game. The results showed that average time to throw and pressure percent were the most influential. With this, I comprised an overall offensive line rating using a weighted summation of the z-scores for each metric. Finally, I scaled the ratings between 0 and 1 to make them more comprehensive and interpretable. If you read my previous article to this series, you’ll notice that these ratings are slightly different than before — this is because the ratings are geared more towards pass protection, rather than run blocking.

Analysis

After creating ratings, I plotted each team’s rating against their expected fantasy points per game. The results show a fairly strong relationship between pass protection rating and expected fantasy points per game. Because of some outliers, the R-squared value is lower than expected, at 0.34. This tells us that 34% of the variance in expected fantasy points per game can be explained by the variance in the ratings. Let’s see if this trend continues when we look at true performance.

Below, I plotted offensive line rating vs. the difference in actual fantasy points per game (passing) and expected. Unfortunately, the trend does not continue. There is little to no correlation between O-line rating and quarterback over/underperformance. It appears that we cannot predict whether a QB will outperform expectation based on their pass protectors.

Let’s break down the numbers a bit more:

61.54% of teams with a rating over 0.5 exceed the mean in expected fantasy pass points, and 50% do for teams with rating under 0.5. This tells us that it isn’t essential to have a strong front in order to have fantasy potential as a QB.

38.5% of teams with line ratings over 0.5 outperform expectation in fantasy passing points, while only 22.2% do for teams with ratings under 0.5. This tells us that being a successful fantasy QB is difficult! Even quarterbacks with strong pass protection struggle when it comes to putting up points in fantasy. It also shows that while passers with good lines may have a slight edge, it is by no means necessary for fantasy success.

Below, you can find the offensive line ratings from the 2023 season, along with the expected and actual total fantasy points per game numbers.

Conclusion

Offensive lines don’t play a large role in fantasy success for quarterbacks. While a good front may give them a slight edge and a higher chance at success, it is apparent that more factors are at play in this regard. Quarterback skill is evidently very important for fantasy success, because regardless of protection, there are passers who still overperform consistently.