The normal Major League Baseball offseason is long and only occasionally punctuated by major transactions. Sure, there are a few periods of higher transactional traffic—namely, around the Winter Meetings, held in December—but there’s not a lot of pressure to sign guys or make trades right out of the gate. Generally speaking, a free agent signing from December is just as likely to succeed as a free agent signing from March.
This is...not the case for the other major American professional sports, whose free agency periods are wild affairs that take place over an extremely short period of time.