Brewers rightfielder Corey Hart had made 3,239 career plate appearances before last week's series with Houston, but never encountered what he saw in his first trip against the Astros. The third baseman, shortstop and second baseman were all positioned between second and third base, a configuration that left an open space as vast as Lake Michigan on the right side. The Astros were deploying an extreme shift on Hart, a righthanded hitter who pulls most of his ground balls to the left side. It was the first time the Brewers had seen the shift against one of their righty batters. It was unexpected, unconventional—and straight out of Milwaukee's own playbook.
Since the beginning of last season, the Brewers have used radical infield shifts more aggressively than any other NL team: Ron Roenicke, who took over as manager in November 2010, switches up his defensive look as often as the Packers do. "It's not rocket science—we're trying to be where we think the other team is going to hit the ball," says infield coach Garth Iorg, who helped the Brewers go from a below-average defense in 2010 to the NL's fourth best in '11, as measured by the defensive metric Ultimate Zone Rating (UZR). "It's been outstanding for us. And it seems like more and more teams are starting to do it. Unfortunately."
Once, teams shifted in rare and specific circumstances—usually to thwart pull-happy lefthanded sluggers such as Barry Bonds, David Ortiz and Ryan Howard. But according to data from Baseball Info Solutions, this season teams are shifting more than twice as often as they did a year ago. "When the data is showing that a guy is hitting 90 percent of his ground balls to one side, it only makes sense," says John Dewan, author of The Fielding Bible and the owner of Baseball Info Solutions, which has been providing teams with data on shifts since 2010. According to Dewan, when the shift is used, there's evidence of a 50-point drop in batting average on ground balls, short liners and bunts.
The shift has been a secret weapon for years for the Rays, who have been baseball's best defensive team over the last four seasons according to UZR. Manager Joe Maddon shifted 50% more often than any other AL skipper last year, and he's doing it more than ever this season. Last week against the Angels, the Rays used an extreme shift against Albert Pujols, who went 1 for 11 with four infield groundouts and line-outs in the three-game series.
The Rays don't just save the shift for elite sluggers—against the Tigers last month, for example, they moved for Jhonny Peralta and Ryan Raburn as well as masher Miguel Cabrera. Said Yankees switch-hitter Nick Swisher after a series against the Rays, "That's the first time I've seen a shift like that. Righties, lefties, it doesn't really matter. It feels like there are 15 guys on the right side of the infield or the left side of the infield."
Not everyone is a believer: As of Sunday the Cardinals, White Sox and Rockies had yet to shift this season, and the godfather of advanced stats, Bill James, argues that the benefits of shifting can be offset by, say, runners advancing to bases left uncovered. "There's still a lot more to be learned," says Dewan, who estimates that there are 100 current major leaguers who should be shifted against but are ignored. "We still need more data. But there is evidence pointing to this as working."