You probably have not given much thought to Ty Law since he retired, and you almost certainly haven’t given much thought to what Law did as a member of the Jets in 2005. But it was a pretty remarkable season.

Law had 10 interceptions that year. That number may not sound like a lot to you — it’s not a record, and we rarely focus on interception totals — but no player has had more than 10 interceptions in a season since 1981. Since Everson Walls of the Cowboys recorded 11 interceptions in 1981, eleven players have intercepted exactly ten passes in a single season. Of those, Law played on the team that faced by far the fewest passes, and he did so in an era where it was very difficult to record interceptions. That’s why, by the metric I’ll describe below, it’s the most impressive interception season in NFL history.

First, I calculated each player’s individual interception rate, defined as his number of interceptions divided by his team’s pass attempts faced. ^[1]Perhaps in a future version, I will adjust for games missed due to injury. The record here was set in 1946 by Pittsburgh’s Bill Dudley, a former first overall pick. That year, Dudley led the NFL in rushing… and punt return yards… and interceptions! Dudley intercepted 10 passes, while the Steelers faced just 162 pass attempts, giving him an interception on 6.2% of opponent dropbacks. Perhaps most amazing, the Steelers leading receivers each had just ten catches, which means Dudley caught as many passes on defense as any Pittsburgh player did on offense in 1946.

Law’s 10 interceptions came against 463 opponent pass attempts, giving him an interception on 2.2% of opposing pass plays. That remains the highest rate in a single season since Walls picked off a pass on 2.4% of opponent pass plays in 1982. But obviously interception rates have been sharply declining, which is what makes Law’s accomplishment so remarkable.

I calculated the league average interception rate for every league ^[2]That is, treating the AFL and AAFC as separate. and every season since 1940. Then, for each league season, I adjusted each player’s interception rate based on the ratio of the average interception rate since 1940 and the league average rate for that season. So, for example, players in 2014 get a multiplier of 2.15, since interceptions are so rare now, while players in 2005 receive a multiplier of 1.76, and players in 1978 get a multiplier of exactly 1.00. Unfortunately for Dudley, he gets a multiplier of 0.60.

So with Dudley, his 6.2% gets adjusted down to 3.7%. For Law, his 2.2% gets adjusted up to 3.8%. And that’s how Law jumps Dudley into the top spot.

The table below shows the top 200 seasons of all time. The table is fully sortable and searchable, and you can change the number of seasons viewed by using the dropdown button on the left.

Ed Reed leads the list with five top-200 appearances. Only two linebackers — William Thomas and Thomas Howard — make the cut. And Deion makes just one appearance on the list, showing that interceptions are only a small part of defensive back play.

What do you think of this methodology? What stands out to you?