Playing the percentages is the winning formula

The numbers rattle around in Heath Farwell's head every time he covers a kick or blocks for a return. The 20 means 23.1. The 40 brings it up to 31.4. Their 40? That'll get you 56.9.

Since the end of last season, Vikings coaches have stressed the relationship between field position and scoring. Special teams meetings, led by coordinator Paul Ferraro, routinely include discussion of a chart that correlates the starting yard line of a drive and the probability it will lead to a touchdown or field goal.

Based on 2006 results, teams that started on their own 20-yard line scored 23.1 percent of the time. When they began on their 40-yard line, the percentage jumped to 31.4; the opposing 40 elevated to 56.9 percent.

Field position is important for all NFL teams, but for run-first teams such as the Vikings, every yard makes a difference. Literally.

"That's really what we've been focusing on," said Farwell, who led the Vikings with 25 special teams tackles last season. "They've really emphasized that since minicamp, in meetings. We'll look at it and say, 'If we pin a guy deep, and then our defense makes them punt, look what it can mean for our offense.'"

There was no bigger coaching point in training camp for the Vikings special teams, which muddled through an inconsistent performance last year. Coach Brad Childress made improving the coverage teams a priority, signing Carolina special teams star Vinny Ciurciu to a lucrative three-year contract and asking more veteran starters to serve on coverage units.

Fueling that prominence was statistical information that illustrates the critical role that field position plays in the outcome of games. Consider the example Farwell outlined:

The Vikings kick off to start the game, tackling — for the fun of it, we'll say Chicago returner Devin Hester — at the 19. Based on the average of all NFL drives last season, the Bears now have about a 23 percent chance of scoring on that drive.

Say the Vikings defense forces a punt three plays later at the 18-yard line. Bears punter Brad Maynard kicks it 43 yards to the Vikings' 39. Even if it is returned only 5 yards, the Vikings start their drive at the Bears' 44.

That field position gives the Vikings offense about a 37 percent chance of scoring on the drive.

Change the numbers a bit, however, and the percentages go down significantly for a team that isn't expected to score a lot of quick-strike touchdowns this season.

Increase Hester's original return to the 35-yard line. Maynard now punts it 43 yards to the Vikings 22. The return puts them at the 27-yard line. Now, after losing 16 yards in the exchange, the Vikings' chances for scoring have dropped to a little less than 24 percent.

"We're always looking at those things and teaching our players just how important those situations can be," Ferraro said.

Then there is the impact of an illegal-block penalty, bringing back a long return.

The percentage of scoring after a return to the 48-yard line is 43 percent. If the penalty brings it back to the 25-yard line, that team's chances have now fallen to a little more than 24 percent.

"That happened to us three or four times last year," Ferraro said, "where there were some critical situations where we had some good returns called back. It changed field position and ultimately cost us some points.

"So we're emphasizing that in a big way this year. Not that we didn't emphasize it last year, but now, graphically, we're showing our players on the board: 'Just look at the percentages. Look at how they change when the field position changes.'"

Kevin Seifert • kseifert@startribune.com