Smoltz, 41, has pitched in 708 games for the Braves, winning 210 games and earning 154 saves. He has been rehabilitating his shoulder since having surgery last season, and there have been reports that he has made excellent progress.
Smoltz's departure from Atlanta would come in a winter in which the Braves have struggled to fill holes in their rotation; Atlanta was unable to land Jake Peavy, after extensive trade talks, and was unable to sign free agent A.J. Burnett.
Boston's proposed deal with Smoltz is for $5.5 million in base salary, and $5 million in incentives.
Assuming the Red Sox close out negotiations with Smoltz, they will go into spring training with six veteran starters -- Josh Beckett, Daisuke Matsuzaka, Jon Lester, Tim Wakefield, Brad Penny and Smoltz. Penny agreed to terms on a one-year, $5 million deal and will be in Boston Thursday for his physical examination.
But the Red Sox have come to believe in the idea of going into each season overloaded with starting pitching; their assumption is that, at some point, injuries will factor in the equation, or some members of the rotation will need rest.
The signings of Smoltz and Penny also give the Red Sox the flexibility to consider trading one of their young starting pitchers -- most notably Clay Buchholz, whose name has come up in trade talks with the Texas Rangers, for catcher Jarrod Saltalamacchia, as well as with other teams.
Buster Olney is a senior writer at ESPN The Magazine.