Few stats measure defensive players in the NFL. You have your sacks and interceptions, sure. You have tackles and assists, but those often depend not on the skill of the player but on what position he plays and what scheme his team runs. Tackle totals don't do anything to look at opportunity -- they tell you only when a defender makes a play, not when he blows one.
We wanted to rectify that, so in 2009, we asked the volunteers of the Football Outsiders' game-charting project to mark broken tackles for the first time. We defined a "broken tackle" as one of two events: Either the ball carrier escapes from the grasp of the defender, or the defender is in good position for a tackle but the ball carrier jukes him out of his shoes. If the ball carrier sped by a slow defender who dived and missed, that didn't count as a broken tackle.
The resulting numbers are subjective, obviously, and we've adjusted the numbers a bit for a handful of charters who were gave out broken tackles either far more often or far less often than the average charter. However, more than two dozen charters were involved, so no team's numbers could be overly slanted because of the bias of a single charter.
Given the mistakes that are easy to make when marking players off television tape, a difference of one or two broken tackles isn't a big deal. But looking at the players with the most and fewest broken tackles does a good job of showing us which defenders were able to wrap up and which ones got run over. And when it came to broken tackles, one player stood head and shoulders above (or, perhaps, below) the rest of the league: Tampa Bay Buccaneers safety Sabby Piscitelli, who had four more broken tackles than anyone in the league. (No. 2 was also a Tampa Bay player, Mr. Ronde Barber.)