Recovering a fumble appears to be a stochastic process (i.e., a random event). This has been analyzed many times and the conclusion remains the same. Consider this excellent excerpt from Pro Football Prospectus 2005 (New Orleans chapter) and listed on the Football Outsiders basics page:
Stripping the ball is a skill. Holding onto the ball is a skill. Pouncing on the ball as it is bouncing all over the place is not a skill. There is no correlation whatsoever between the percentage of fumbles recovered by a team in one year and the percentage they recover in the next year. The odds of recovery are based solely on the type of play involved, not the teams or any of their players.
Note that forced fumbles (FF) aren't exactly a stochastic process: "Stripping the ball is a skill." FF can be the result of physical, violent play where the offensive player is roughly separated from the ball:
FF can also be the result of intentionally stripping the ball out of the offensive player's hands. In a 1-on-1 setting, this can be risky as the ballcarrier may coast on by your
Stripping the ball is best employed (i.e., lowest risk of breakaway from a missed strip) in a gang-tackling situation.(1:21 mark)
Of course, down+back+kick-button can also produce desired results.
Everyone knows that turnovers can over/underrate a defense. But FF turns out to be quite important. How important? A 2007 study on NFL teams (Advanced NFL Stats) showed that FF demonstrated a strong correlation to team wins and defensive points allowed.
So what defenses are helping to liberate the pigskin? Let's take a look at FF in the college ranks from 2006 to 2010. More after the jump.
Texas sits atop the rankings. The Longhorns have pretty consistently run a great defense out on the field, as evidenced by their Defensive FEI rankings since '07 of 42nd, 3rd, 10th, and 31st. And with basically carte blanche to the states' top recruits, they should field a great defense.
It's also interesting to note that Tennessee, Georgia, and Florida do NOT force that many fumbles. Duke and UVa. pull up the rear in the ACC and are sub-100 nationally. USC, Purdue, and East Carolina rank in the top quarter or so of FF, but also demonstrate some of the largest variances. ECU really dropped off this past year, as they only had 3 retuning starters on the 2010 season. And we stole their DC.
Florida State demonstrates one of the largest variations in FF during the 5 year period (not shown), with an '06 minimum of 6 and an '08 maximum of 20. The most consistent FBS team is Baylor, though they average slightly less (10.8) than the mean number of FF (12.3) over the 5-year period.
If you're a TN-regular or upright thinking football-type, you may be asking yourself, "But what about the number of plays a defensive unit sees?" Opponents that can score quickly, run up-tempo schemes, or if your offense turns the ball over frequently, puts their defense in a position of having to take a high number of snaps. In 2010, FSU's defense saw the #3 most snaps of all FBS defenses. Consider that FSU ran the 100th-ranked offensive pace (i.e., very slow), and you realize that Jimbo and Co. was trying his best to shelter his new scheme and young personnel. OU and other teams aimed to force our defense to take as many snaps as possible. FSU was able to right the ship, though, in the 2nd half of the BYU game. After seeing no-huddle for much of the first half and keeping the game close (13-10) going into halftime, FSU would go on a reel of 8 consecutive quarters of 0-point ball (2 vs. BYU, 4 vs. WF, and 2 @ UVa).
Back to that Advanced NFL Stats article: The rate of defensive forced fumbles (i.e., FF per defensive play) proved to be the strongest variable toward determining defensive ranking and total team wins. We know that the amount of plays a defense sees can reflect their own team's offensive pace (i.e., HUNH-offenses will increase the number of possessions (and thus plays) for both teams at play). So, taking into account the number of snaps a defense sees, how does FSU's rate compare? Who has the #1 rate of FF? In 2010? Since 2006?
Some very interesting things show up once we take into account FF per Play (FFpP). For instance, since 2006 Texas (2.05%) has forced more than twice as many FF per play as Florida (1.02%) .
Virginia Tech actually moves up in the rankings once taking into account the amount of plays the defense faced. Bud Foster has to be considered one of the best college DCs ever. Can you name someone who has consistently gotten more out of a defense that has never won a recruiting championship? Their '06-'10 average was 19th.
FSU actually falls a few rankings, though still above the median ranking.
Please feel free to share your thoughts/insights. Here's a link to the data, if you're interested in that sort of thing (not that there's anything wrong with that!).