The Yankees and the Red Sox both have to worry about key players who are either aging or injury prone.
The Yanks have CC, Kuroda, Ellsbury, Jeter, Beltran, and Soriano who could all be big question marks midway through the season because of age and injury concerns.
The Red Sox rely heavily on Ortiz and Koji, while Pedroia and Victorino seem like big injury concerns as well.
Meawhile, the pesky Rays lose a crucial arm in Moore, the Jays are without Reyes and the O's are without Machado.
This season will come down to luck.