The Red Sox needed a veteran to catch their championship team, and ultimately they liked the idea of Pierzynski, an excellent offensive catcher who has respected game-calling skills, handling their staff.
In the end, they probably needed to either sign Pierzynski or bring back Jarrod Saltalamacchia, who was a part of their championship team last year. Early on, they offered a two-year deal to Salty.
Boston was always hesitant to do a very long deal with a catcher as it is has two very good catching prospects, Blake Swihart and Christian Vazquez, who could be ready fairly quickly. The Red Sox also have a strong backup in David Ross.
The Twins, Marlins and White Sox are among teams still looking for a catcher, so Saltalamacchia has a few options.