Top factors for underdogs
Diving deeper into the group stage numbers, we can also figure out what kind of play is working best for underdogs in this tournament. Beyond overall team strength, four factors are boosting would-be Cinderellas in Brazil, according to our research.
• Tackles: Aggressive defense, as we have noted, is key to keeping a Goliath in check. So, not surprisingly, tackles are the most important defensive metric in any David's slingshot. With a tackle, you take possession of the ball away from your opponent without committing a foul; it's the equivalent of a basketball turnover, which has proved to be one of the largest factors involved in an upset in the college game. Nigeria is in the round of 16 because they upset Bosnia-Herzegovina 1-0, in a game the Super Eagles secured by making 21 tackles. Conversely, Chile maintained possession of the ball for 64 percent of their game against the Netherlands -- but still lost 2-0, largely because they had just four tackles and hardly disrupted the Dutch.
• Average shot distance: It seems obvious that the closer you take your shots, the more likely you are to score. But the power of a short average shot distance is so large it bears emphasis. The numbers say it doesn't matter much if a team makes a lot of short passes, like Germany, or fewer longer passes, like Algeria, just so long as its possessions terminate with shots inside of 20 yards from the opposing goal.
• Offsides: Draw an opponent offside and you gain possession and a free kick; the perfect recipe for stalling the momentum of a superior antagonist. A hidden but huge key to American success so far: The U.S. has been caught offside only three times in three games, versus 16 for its opponents.
• Home hemisphere: Teams from the Americas are having an unexpected level of success at this year's World Cup. Maybe it's the fans: South Americans are packing Brazil's stadiums, and seem to be rooting not only for their own home countries, but for neighboring nations that are underdogs against European teams. Or perhaps it's the jet lag: It's significantly easier on athletes to travel from north to south than from east to west. Or it could be the heat. Still, no matter the cause, CONCACAF and CONMEBOL squads are essentially playing with home-field advantage.
Please note: We are not claiming these are the only stats that matter to soccer teams. Possession in the attacking third, pass completion percentage, aerial duels won, yellow cards -- these all have their (significant) place in soccer analysis. But SPI incorporates, directly and indirectly, many such aspects of play. What we are isolating here are the qualities that have widened the gap between expectation and reality, predicted play and actual results.