Winter, spring, summer or fall. It’s not just a James Taylor lyric.

That’s when stuff — really, really big stuff — can happen across Major League Baseball and completely alter the league’s future. Teams always are looking to improve, and this past offseason featured several moves that could have wide-ranging ramifications in 2015.

Jon Lester is in Chicago trying to end the Cubs’ 106-year World Series drought. Max Scherzer left the Motor City for the nation’s capital. The Boston Red Sox shelled out almost $200 million to obtain the services of Hanley Ramirez and Pablo Sandoval.

While those deals represent only a small taste of the baseball activity since the San Francisco Giants clinched their third World Series title in five seasons back on Oct. 29, they also create a perfect snapshot of how wild this winter has been for MLB.

So, which moves were the biggest? What are the X factors going into this season? Who are the favorites to punch their tickets to October?

NESN.com’s Ashley Allen recently caught up with Red Sox beat writer Ricky Doyle to discuss the 2015 MLB season. Check out the videos and links below for a breakdown of each division’s big happenings.