The Red Sox and Yankees have waged their version of a baseball arms race for decades, with the moves and countermoves dating to the start of free agency.
The Red Sox signed Mike Torrez away from the Yankees, and a year later, the Yankees took Luis Tiant away from Boston. The two sides notoriously fought with checkbooks over Jose Contreras after the right-hander defected from Cuba before the 2003 season. Not long after the Expos told the Red Sox that they didn't have enough to trade for Javier Vazquez, Boston made a deal for Curt Schilling. The Yankees dominated the winter two years ago by signing Mark Teixeira -- Boston's primary target -- as well as CC Sabathia and A.J. Burnett, and in turn, the Red Sox have owned this winter, taking on Adrian Gonzalez and Carl Crawford.
That kind of thing has been going on in other divisions this winter, as well: The Cubs' acquisition of Matt Garza to strengthen their rotation seemed to come in response to the development of the Cincinnati staff, and the Brewers' move to add Zack Greinke. The Tigers got Victor Martinez, and it wasn't long after that that the White Sox landed Adam Dunn.
The strategy of mutual deterrence has been in play in the AL West, too. The Rangers' trade of Frank Francisco for Mike Napoli doesn't address Texas' primary question, namely rotation depth. But Napoli will undoubtedly strengthen Ron Washington's lineup against the team that represents the greatest threat to Texas.
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