The Art Of The Interception: Luck And Stone Hands

I thought I would take a few minutes to play out the idea we discussed a couple of days ago: the relationship between interceptions and passes broken up.

PBUs are sometimes dropped interceptions. In 2011, the 120 FBS teams intercepted 1,436 passes and "broke up" 5,131. That means that 21.9 percent of what we call "passes defended" were interceptions. Only, the spread from team to team was enormous. For N.C. State, 43.5 percent of their passes defended were INTs. For Akron, 6.7 percent.

I looked at this data from year to year and found that, though it would appear based somewhat on skill (N.C. State had David Amerson and Akron didn't, after all), a team's year-to-year percentages have almost no correlation. Georgia's Bacarri Rambo was second in the country in interceptions (eight), but in his three years of participation, the Bulldogs' ratio of interceptions to overall passes defended has gone from 19.6% in 2009, to 35.6% in 2010, to 27.0% in 2011. Some years, you catch them. Others, you don't.

So what that means here is that we are going to look at a team's ratio of interceptions to passes defended and apply it to the Adjusted Turnover Margin as well. Even with Amerson, we can safely assume that part of their ridiculous 27 interceptions were caused by luck, and as we know, luck is incredibly fickle.

I am using this idea to build into my 2012 team profiles, but let's spend a few minutes looking at individual players. Below are players who 1) ranked in the nation's Top 50 in Passes Defended last year and 2) are returning in 2012. I simply took a look at the number of passes they defended per game in 2011 and projected how many interceptions they should have had if they had pulled in 21.9% of their passes defended. This comes with some obvious disclaimers:

1. Not everybody has the same set of hands. Some defensive backs have great hands, while others are defensive backs (and not receivers) because their hands leave something to be desired.
   
   
2. If we were to use this as "projections" for 2012 -- as in, how many passes might they intercept next year? -- we would have to assume that they will see the same number of passes in 2012. That might be a faulty assumption because, quite simply, you develop a reputation after a while. Players on this list got quite a few opportunities to prove what they could do. Next year, someone like Merrill Noel, E.J. Gaines or David Amerson (i.e. a player who came out of nowhere in 2011) might not get as many opportunities to break passes up, simply because opposing quarterbacks might be choosing to look toward the other side of the field. That is one of the limitations of using individual Passes Defended data -- a lot of the country's best defensive backs didn't make this list because quarterbacks did not try to throw at them very much (because they're among the country's best defensive backs). Still, consider this a thought exercise as much as anything. It suggests that players like David Amerson and Bacarri Rambo may have been a bit lucky in both the opportunities they received and the balls they actually pulled in. Meanwhile, players like Merrill Noel, Josh Robinson, Najja Johnson or Marc Anthony either have awful hands or might pull in a couple more picks next year (if given the chance).

Just found it interesting on a Saturday morning, is all.