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The turnover battle: crucial, yet unpredictable

Posted by Andrew Mooney  January 4, 2012 01:01 PM

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You’d have to examine this year’s GOP field to find a frontrunner inspiring this much doubt. For the second consecutive year, the Patriots have earned the AFC’s No. 1 seed, and the overwhelming fear is that, for the third consecutive year, the Pats will bow out in their first postseason contest.

The cause of this agonizing is unquestionably the Patriots’ defense, which just finished a campaign in which it allowed more yards (6,577) than any team ever to make the playoffs. If, for some reason, Tom Brady and the offense should falter in concocting one of the blistering comebacks we’ve seen the past few Sundays, the Pats may be spending their February weekends on the golf course rather than the gridiron.

Burdened with this historically porous defense, the Patriots’ Super Bowl hopes may hinge on a fickle, yet vital aspect of the game: the turnover battle. If you’re searching for a statistical trend underlying the Pats’ current eight-game winning streak, look no further: the Patriots have turned the ball over just three times on offense, while the defense has forced 20 turnovers over that same span, for a margin of plus-17, the best mark in the NFL over this period.

Recent history certainly testifies to the importance of the turnover battle. In two of the last three weeks, the Patriots’ early deficits were quickly reversed with the help of timely takeaways. Tim Tebow’s Broncos watched a 9-point lead evaporate into an 8-point deficit in the span of seven minutes after two fumbles in their own territory. Against the Dolphins, a third quarter fumble by quarterback Matt Moore positioned the Pats for their first touchdown and turned a game that had threatened to become ugly in the first half into a one-score game.

Just how crucial are turnovers to a game’s outcome? The chart below shows teams’ winning percentages in games with a given turnover margin, derived from a ten-year sample of games from 2002 to 2011. Assuming equally matched teams, forcing just one turnover more than the opposition boosts a team’s chances of victory 19 percent (50 to 69 percent). With a turnover margin of plus-2, a team’s chances of victory rise to 84 percent, and at plus-3 or above, they are virtually secured at 93 percent.

This would seem to favor the Patriots, whose plus-17 turnover margin this year ranks third in the NFL. However, analysis done by Football Outsiders suggests that, for as critical as turnovers are to a game’s result, they seem to be more attributable to random chance than to players’ skill.

A bit of clarification: if the ability to force turnovers were a skill, we’d expect to see it show up on a consistent basis, over multiple seasons. But the year-to-year correlations for turnovers, especially on defense, are actually quite weak, meaning the numbers from one year have very little ability to predict those of the next year. (For those interested, the exact figures can be found here.) Offensive turnovers are slightly more predictable, due largely to a quarterback’s ability to limit his interceptions, but on defense, takeaways essentially occur at random. In other words, the Patriots haven’t been “good” at forcing turnovers; they’ve been lucky.

The only real measure of control over turnovers lies with quarterbacks in avoiding interceptions, and fortunately for the Patriots, they have Tom Brady, whose 2.2 percent career interception rate is the third-lowest in NFL history. Even if the Pats’ luck runs out on defense, Brady gives them a better chance of maintaining a favorable turnover margin.

But it’s important to remember that much of the early-season panic surrounding this team — if it’s possible to panic after a 5-3 start — was a result of Brady’s uncharacteristically poor protection of the football. Brady’s four interceptions were almost solely to blame for the Patriots’ Week 3 loss to what has proved to be a considerably inferior Bills team, and the fact that two of them came on batted balls — which could just as easily have fallen harmlessly to the turf — underscores the role luck can play in swinging games.

Likewise, in the one-game, do-or-die format of the NFL playoffs, the best teams don’t always win. Flukes happen; sometimes Brady throws four picks. As cruel as it sounds, chance could easily determine the outcome of the Patriots’ playoff run. If the bounces continue to favor the Pats’ defense, they’ll be able to curb the scoring of the opposition (if not their total yards) and not overly disadvantage Brady and the offense. But an ill-timed deflection of a Brady pass could portend yet another early exit.

This blog is not written or edited by Boston.com or the Boston Globe.
The author is solely responsible for the content.

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Stats Driven is powered by David Sabino, who over the last two decades has been a source of statistical analysis on the pages of Sports Illustrated, New York Times, and Chicago Tribune. David has written about all seven recent Boston-area championships for Sports Illustrated Presents commemorative issues, was the creator of such long time features as SI’s Player Value Ranking, NBA Player Rating and long running fantasy football and baseball columns.

He has also authored or made contributions to many books, including the Sports Illustrated’s 100 Fenway: A Fascinating First Century.

Now living in Marblehead, he’s focusing his attention on the Boston sports scene, specifically delving into the numbers affecting the Red Sox, Patriots, Celtics and Bruins, with the goal of informing and entertaining real fans. You can follow him on Twitter at @SabinoSports.

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