I think such worries are overblown. Here's why...
Looking back on last off-season, clubhouse chemistry was an important factor in player acquisition, but it was not the only factor. Fans and media seem to ignore/forget that the Sox signed good players, who were also good clubhouse guys. These were not lovable, talentless losers. These were skilled, experienced, capable players.
The chemistry the Sox enjoy doesn't seem like it's delicately balanced, on the verge of collapse like a house of cards if one piece is removed or added. It seems much stronger than that. Resilient is the word I'd use. As much of a prick as Pierzynski is, I don't think a part-time catcher will be able to cause much division or strife.
Predicting clubhouse chemistry is not a science. Actually, it is. It's called psychology. And psychologists have labored for decades trying to figure out how people's interpersonal relationships work and why. However, sports media and fans think they can predict these things. It's so simple.
You can't predict clubhouse chemistry. John Lackey, Josh Beckett, and Jon Lester got along great. And that was bad for clubhouse chemistry. Remove Beckett and suddenly Lester and Lackey become character guys. Pedro Martinez and Curt Schilling did not get along yet the chemistry was fine on the 2004 Sox. Dustin Pedroia was seen as a manager's pet in the 2011 clubhouse, then as anti-manager/rebel in 2012, now as a leader in 2013.
Baseball analysts have a hard time predicting on-field performances. Off-field relationships (and their impact on on-field performance) are considerably less predictable.
The fact is, Pierzynski is signed for just a year. He can play. He can hit, he can call a game, he can throw runners out. I liked Jarrod Saltalamacchia (my spell-check didn't), but he was what he was. Salty struck out a lot, was an inconsistent hitter, and wasn't trustworthy defensively in a big game. Salty was not a mid-term or long-term solution. I don't think Pierzynski is a superior player, but the Sox signed him to a placeholder deal, and that's the difference.
The Sox have catching prospects in the pipeline. Pierzynski fills in the gap until they arrive, or until another solution is found. I doubt in one year he'll be capable of doing much damage to the clubhouse. And if he does, he'll be designated for assignment. I wouldn't want a multiple Pierzynskis in my clubhouse, but I think one is manageable, containable.
