The Cardinals make a lot of sense as a trade partner for the Red Sox
It appears as though the Cardinals have finally read the writing on the wall and should be selling in some capacity at the trade deadline. They are firmly in last place in the National League Central and even if they were to put together a bit of a run, the Reds and Brewers are in a much better position for a playoff push. However, that doesn't mean that the Cardinals don't have talent on their roster and Boston should try to take advantage.
The Cardinals "probably" don't want to trade too many guys who have team control beyond this season, but they have a ton of guys who are about to be free agents. Jordan Montgomery should be at the top of the Red Sox's wish list to bolster their rotation. Jack Flaherty was a hot name a few years ago, but he hasn't pitched well in a few seasons. Jordan Hicks and Chris Stratton are interesting bullpen options as well that shouldn't break the bank.
The Red Sox could make a deal with the Giants that could benefit both teams
The San Francisco Giants have remained competitive in the loaded NL West, but they find themselves in real need of an impact bat especially with Thairo Estrada out for at least another month. Moreover, they are also rich in pitching prospects. Getting Kyle Harrison and probably Carson Whisenhunt is probably off the table, but the Giants still have a number of arms in the high minors like Mason Black, Landen Roupp, Keaton Winn, and Carson Seymour that could be interesting to Boston.
The obvious name that could make sense for the Giants would be Adam Duvall as he is one of the few bats who could be available at the deadline that could move the needle. However, the Giants could also need another starting pitcher especially with Harrison getting hurt right before the All-Star break, but the Giants still have enough pitching prospects to make a deal work without disrupting their short-term plans too much.
The Padres are all-in and Boston should take advantage of that
One of the bigger disappointments this year have been the San Diego Padres. Despite all of their wheeling and dealing, the Padres find themselves in fourth place in the National League West. However, there is no denying the star power that is on their roster and San Diego has shown no indication whatsoever that they are throwing in the towel.
With the Padres looking to buy, Boston has an enthusiastic trade partner. Guys like Justin Tuner and Adam Duvall make sense as options to send to the Padres to give them a DH that can actually hit. The return from San Diego would likely not be guys who could help this year, but San Diego is rich in guys that are further away but have tons of potential with Adam Mazur, Sam Zavala, and Jairo Iriarte being among the most interesting options.