With 12 games under our statistical belts, I thought it's a good time to check in on a new concept I unveiled in the off-season. Tackle Factor (TF) is a stat that tries to make better sense of the NFL's tackle numbers. Let's see how this season's top defenders are faring in TF. If you're already familiar with TF, skip down to the tables of top players.
You might think that more tackles is always better for a player, but it's not that simple. Some positions simply get more tackles by their nature, especially linebackers. Plus, some defenses are worse than others, allowing more 1st downs, more plays, and by definition, more tackles to be had.
TF begins to untangle tackle stats by looking at a defender's share of his team's tackles. This accounts for the number of plays (and tackles) allowed by each defense. It then compares each defender's share of team tackles to the expected share of tackles by a player at his position. TF excludes special teams tackles and offensive tackles on turnovers. A TF of 1.0 would theoretically be average, but only if a defender has played in all of his team's snaps. TF is also adjusted for games played, so a player who has missed a few games due to injury isn't penalized.
One other additional benefit of TF, one that I did not even think of when I first implemented it, is that it normalizes for hometown scorer tendencies. Tackles are technically not considered official stats by the NFL. Each team has its own scorer for home games, who decides whether each tackle is recorded as a solo or who, if anyone, gets credited with an assist. So tackle stats are not purely objective. (This is not to suggest the scorers are biased in any way. Rather, the point is there are 32 slightly different standards for what qualifies as an assist.) Because TF is based on a share of team tackles, scorer tendencies are mitigated.
TF is not perfect. Some team's schemes call for certain positions to be space-eaters and some to be play-makers. There are other shortcomings too, most of which are discussed in the comment thread of the original post. Despite its flaws, it can still give us a good sense of who has a nose for the ball.
Also, TF really only makes sense for front-seven defenders--DEs, DTs, and LBs. For individual defensive backs, it tells us something completely different. In the future, it could be restricted to run plays or even to 'victory' tackles, which limits the analysis to how many tackles are made on plays that result in an advantage for the defense. This might make better use of tackle data for DBs. For now, we'll just look at front-seven guys.
As an example, this season Jarod Mayo of the Patriots leads all linebackers with a TF of 1.87. This means that Mayo has recorded 87% more of his team's tackles than you would expect from a player at his position. To calculate Mayo's 1.87 TF, we start with the Patriots' total of 695 defensive tackles and assists this season. Mayo has 94 solo tackles and 49 assists, accounting for 20.6% of his team's total. LBs, whether in a 3-4 or 4-3 scheme, tend to get about 11% of their teams' total tackles. 20.6/11 = 1.87. Mayo has played in all 12 of the Patriots' games so far this season, so no game adjustment for him is needed.
Here are the top linebackers, who tend to gobble up the most tackles of any position.
There's the usual suspects: Willis, Lewis, Posluszny, and Urlacher. And Dhani Jones seems to be playing as much football lately as Does It Smell Anymore? DeMeco Ryans is one of the top LBs in TF, adjusted for only playing in 6 games. The Texans were 4-2 when Ryans went out. Since then they've been 1-6.
Next up are the defensive tackles.
Haloti Ngata leads all tackles with 1.46. Notice that Ahtyba Rubin has more total tackles, but the Ravens evidently have needed to make fewer total tackles to date. The Oakland defensive line looks pretty stout with both Richard Seymour and Tommy Kelly on the TF leaderboard. Usually it's good news when your defensive linemen are the ones making stops rather than LBs or DBs. Rookie Ndamukong Suh has a bunch of tackles to go along with his 8 sacks. The Bills' Kyle Wilson just missed the list, but he's actually tied with Suh at 1.31.
Lastly, here are the defensive ends.
Trent Cole leads the pack at 1.48. And wow, another Raider, Matt Shaughnessy is on the list. Some big names top the defensive end TF ranking, including Tuck, Vanden Bosch, Allen, Edwards, and former 1st round pick Glenn Dorsey.
TF stats are available all season long and for previous seasons back through 2000. Just go to the individual defender stats pages for each position, and click on the TF header to sort.
Defenders By Team