Great article over at ESPN today (full article only for ESPN insiders) on Park Effects - the way ballparks increase or depress offense. Most casual fans know that Coors Field in Denver enhances scoring, while Safeco Field in Seattle doesn't. The article examines whether changes to the dimensions at Safeco and Petco Park in San Diego this season have affected offense. (They have, though not as much as I would've guessed.)
What's really interesting is how the increase in defensive shifts have affected offense. You know all those plays where there are three infielders liked up between first base and second when left-handed hitters like David Ortiz and Ryan Howard are at the plate? They appear to be working. From 2009-2012, major league hitters batted about .130 on fly balls that remain in play. This year, it's below .100. (Remember, a lot of those non-homer fly balls are hit to the infield or short outfield where all those infielders are.) The batting average on line drives is below .700, which hasn't happened before.
So next time you hear about cheap homers hit in bandboxes, it's also become tougher to get hits on balls that stay in play.