Since I’m also writing about other sports, I’m going to take the opportunity to see how we can use data in other sports as well. What can we learn from identifying and analysing talent in the NFL? In this article, I will have a look at QB Purdy at the San Francisco 49ers and attempt to answer the following question: is he a good quarterback, above average, or does he profit from a good attacking system?
I’ve been speaking to a friend who posed the question and it’s an interesting hook. So in this article I will attempt to answer this. As always I approach this through the lens of data and statistical analysis, so this might different from the things you might experience while watching him or the San Francisco 49ers.
Data
The data I use is aggregated data and was collected on December 27th, 2025. It comes from the NFL API and was retrieved using the programming language R from the package NFLReadR. I wrote the code in a way that I got three different databases:
- Play-by-play stats
- Player Aggregated stats
- Team Aggregated stats
I saved them to excel files, but you can easily use CSV as well, which might be even more efficient too.
Effiency King?
How can we measure how much a QB adds to offensive plays? We do that with the metric Expected Points Added (EPA). We can do this through passing and rushing, but for a QB, passing is much more potent. It’s the gold standard for measuring a QB’s impact on scoring.
We can have a look at how 49ers have been doing throughout the season on EPA first:
What we can see in the graph above, is how the passing EPA has been throughout the season so far. What’s interresting is that 49ers had a drop after MD11, but are now climbing again in terms of passing EPA after MD15. Really getting better,
Now the next question is, how does Purdy involve himself in that trend of the 49ers.
When we looking at the EPA per pass attempt, he scores the highest of all QBs. That’s a worthy notion of his qualities. However, this doesn’t show us yet whether this is on par with the idea of 49ers doing well or that he does better than his team might expect.
That’s where look at Completion Percentage Over Expected (CPOE). This is a metric which measures skill. This calculates the expectation that a pass is completed and whether the actual result is above/under expected. Purdy has a completion of 67,8% which is more of traditional metric. In this scatterplot below we can show more about CPOE:
We see that he scores above average for air yards per attempt and way above avearge for CPOE. This means that he is aggressive in terms of yard per attempt, and he scores above average for the expected pass completion. He completed 8,7% more passes that
If he were just a “system” guy, his CPOE would likely be closer to 0%. A high CPOE means he is completing passes that the average NFL quarterback, in the exact same SF system, expected to miss.
Debunking “YAC Merchant” Myth
There is this myth that Purdy would play short passes and let his teammates do the hard work. But how true is this?
You can see the Air yards per attemp against the system reliance. While Purdy isn’t the most aggressive downfield player, what’ s evident that he doens’t rely as much on the system. Purdy sits in the bottom-right quadrant. His YAC (39,8%) is nearly 7% lower than the league average, and his Air Yards per Attempt (7,93%) is higher than average.
Purdy is earning his yards through deep and intermediate passing, not just by handing the ball to playmakers in space.
Pocket presence and protection
The data reveals that Brock Purdy possesses elite pocket presence, evidenced by a remarkably low sack rate of just 3% in the 2025 season. While critics often attribute a clean pocket to a team’s offensive line or scheme, a quarterback’s ability to avoid sacks is widely considered an individual skill related to processing speed and internal timing. With only 7 sacks suffered over the recorded period, Purdy ranks among the best in the league at preventing negative plays, significantly outperforming many of his peers who see sack rates climb into the double digits.
Final thoughts
The 2025 data tells a clear story: Brock Purdy isn’t just riding the wave of a great system; he’s the one creating it. Leading the league with an EPA per attempt of 0.286 and a massive +8.7 CPOE, his success is evident in his elite ball placement and processing, rather than relying solely on safe check-downs or a dominant run game. In fact, with a sack rate near the bottom of the league and a reliance on YAC that’s actually lower than most of his peers, it’s hard to argue he’s anything but a top-tier individual talent. The data proves Purdy is a high-level processor who thrives on the exact high-pressure, high-difficulty throws that separate good quarterbacks from truly great ones.