St. Louis, the Los Angeles Dodgers and San Diego appear to be the frontrunners to land Wells, the source said.
Wells, 43, cleared waivers on Aug. 3, at a time when he was just starting to come back from a serious knee problem; on July 31, he allowed eight runs in 4 2/3 innings. Because he cleared waivers, he can be traded to any team without restriction, and Wells has pitched much better of late. He has a 2.65 ERA in the month of August, walking five and striking out 20 in 34 innings.
The notion that the Red Sox might consider trading Wells would've seemed ludicrous two weeks ago, but Boston is in freefall and has dropped six games behind the Twins in the wild-card race, and seven games behind the Yankees in the AL East. Wells has talked about retiring at the end of this season, so if the Red Sox keep Wells through the month of September and don't make the playoffs, they would effectively lose him for nothing.
And Wells has high value right now, at a time when the likes of Shawn Chacon and Ramon Ortiz are the only pitchers who typically get through waivers. Wells' exceptional postseason history has to intrigue teams: In 16 postseason series, he has a 10-4 record with a 3.15 ERA. In order to be eligible for postseason play with another team, Wells would have to be traded by Aug. 31.
In the end, the Red Sox may decide to keep Wells. But their recent conversations with other teams have been aimed at laying the groundwork for a possible deal if they decide to move the left-hander.
The other contending teams who have expressed interest in acquiring Wells include the Mets, Twins, Diamondbacks, Phillies, A's and the Reds.
Buster Olney is a senior writer at ESPN The Magazine.