Want to see how passing has changed in the NFL over the last 63 years? A picture is worth at least 1,000 words in this case. The graph below shows the number of interceptions per dropback (red), sacks per dropback (purple), non-INT incomplete passes per dropback (yellow) and completions per dropback (green). Of course, a dropback is simply a pass attempt or a sack. The information is stacked on top of each other for ease of viewing.
Update: People often wonder what’s the point of twitter. Well, a few minutes after I tweeted this post, Trey suggested that it might look better as a stacked area graph. I didn’t know what that was, but after trying it in Excel, I’m with Trey. Here was the original graph (which still has some value if you really want to trace a specific year):