A couple of weeks ago, we broke down QB Rating (or Passer Rating, if you prefer) to show the formula and how it works. You can link back to that story here for a full breakdown or just reference the final visual below for a refresher.
QB Rating overall continues to increase as offenses gain efficiency and league rules change to favor offensive football. What exactly does that growth look like? It’s somewhat shocking to look at the steady march of QB Rating over time as QBs make what was once unheard of commonplace. Below charts all qualifying QBs since the NFL-AFL merger completed in 1970.
Each of the blue dots represents a QB’s rating for that season with some of the outliers called out in the data label. The dotted red line is a simple trendline, showing the growth over time. That shows us what we all know intuitively - namely that QB Rating is increasing.
I decided to create a composite QB Rating from all qualifying quarterbacks for each year since 1970 to see what the overall trend looks like. To be specific, I took all qualifying QB data and added them together into one giant QB stat line and calculated the QB Rating from that number for each year (as opposed to taking the average of the ratings, for example). The chart below shows what that looks like.
I labeled the points at 10-year increments for easy visual checkpoints. Note that I started the y-axis at 50 just to get a little more spread on the chart for visualization purposes. What’s interesting here is that there’s a jump in the late 1970s, likely from the West Coast offense, which then grew slowly for awhile until the mid ‘00s with another leap starting around 2012.
We know that QB Rating is made up of four individual components (see first visual). Are they all growing over time? Are some influencing this spike in the QB Rating number more than others? I’m glad you asked. Below, each composite score is broken down by component on the graph.
Here’s the payoff. Why is quarterback rating increasing over time? It’s an increase in the overall completion percentage and a reduction of interception percentage. The yards per attempt and TD percentage components have largely remained steady over time.
Is it coaching or sophistication of scheme? Skill level of the quarterbacks or the pass catchers? Rule changes? Wide receiver gloves?! That’s an interesting debate for another time, but what the math reveals with certainty here is that the growth comes from only two of the four components. How much higher either of those two components can go or if there can be growth in the two stagnant components remains to be seen.
Keep the conversation going and find me on Twitter @gridironborn.