First, the in-game management: With Napoli, the Sox are likely to have three players on their roster who can catch — Napoli, David Ross  (signed earlier in the offseason to a two-year, $6.2 million deal) and either Jarrod Saltalamacchia  or Ryan Lavarnway. That, in turn, means that the Sox can make more aggressive strategic moves during games with regards to either pinch-hitting or pinch-running for their catchers, since they won’t be leaving themselves in a position of being short on the roster (particularly if the Sox have a versatile player on the bench — someone capable of playing both infield corners or first base and the outfield) by replacing their starting catcher on a given day.
Meanwhile, Napoli also added to the Sox’ intriguing effort to corner the offseason catching market. With Ross and now Napoli, the team has taken two of the best available catching options off the board. Russell Martin  has now signed a two-year, $17 million deal with the Pirates. There are going to be teams who lose the free agent game of musical chairs.
The Mariners  (who wanted to sign Napoli as a catcher), Mets, Yankees, White Sox  and Dodgers, according to major league sources, are expected to be in the market for catchers. With Napoli and Ross now added to a roster that already featured Jarrod Saltalamacchia and Ryan Lavarnway (as well as minor leaguers Dan Butler and Christian Vazquez on the 40-man), the Sox are positioned like virtually no other team to strike deals involving catching.
In all likelihood, the trade market for catchers will develop once free agent A.J. Pierzynski signs. He’s the top remaining catcher on the market. Behind him, the market features mostly backup types (Kelly Shoppach , Miguel Olivo, etc.). That being the case, once Pierzynski signs, the Sox expect that they’ll be able to see where the market stands for their catchers — most likely, Saltalamacchia or Lavarnway.
Saltalamacchia has shown the ability to make an offensive impact at the big league level, something that Lavarnway has yet to do. Still, his rough end to 2012 wouldn’t necessarily deter teams that have been tracking him for years and believe that he will be able to hit at the big league level. Both the Mariners (who tried to get Lavarnway from the Sox at the 2011 trade deadline) and Mets believe in his offensive track record and members of both organizations believe he can be serviceable behind the plate.
Lavarnway, based on the fact that he would be under team control for six years and would cost next to nothing in 2013, would have the greatest trade value. (It’s worth noting, for instance, that the Mets could afford him but not Saltalamacchia.) Still, given the positional scarcity and his demonstrated power, Saltalamacchia (who will be eligible for free agency after the 2013 season) will also be a viable option for teams looking for a short-term option at the position. It’s worth noting that the Sox have not had talks with Saltalamacchia about an extension, and given the glut of catchers, they are not expected to do so this offseason.
The dominoes haven’t yet fallen to bring the catching trade market to critical mass, but the Red Sox just gave them a nice push in removing Napoli from the market.