The Mets are out of the race in the National League East, and the Red Sox are fighting for their lives in the American League Wild Card race.
Wagner, 38, was once an elite closer but has had Tommy John surgery and is just coming back now from a long road of injuries. He should provide additional depth to the Red Sox bullpen down the stretch.
However, where the boring details end is where the story begins in Boston.
Wagner didn't want to waive his no-trade clause to go to Boston, and he exchanged words through the media with incumbent Sox closer Jonathan Papelbon.
In fact, in order for Wagner to agree to the move, the Red Sox had to give the reliever assurances they would not pick up his option for 2010.
The Red Sox did, however, retain their ability to offer Wagner arbitration after this season.
There has been speculation that the Red Sox intend to eventually promote super prospect Daniel Bard to the closer role, and could look to move Papelbon this winter if the right move became available.
Wagner has been rumored to be a potential stop-gap closer for the Sox next year, if he'll accept arbitration.
Are there any teams that might want to make a trade for a top-tier closer?
The Red Sox have a decision to make about their ace, Josh Beckett, this winter as well. He has a $12 million club option. There is little doubt that the Sox will retain his services for 2010, but after that he might get expensive.
What if the Red Sox could make a trade for a top-tier starter while shedding salary from their bullpen in the process?
Let's make a deal!
The Chicago Cubs are saddled with some of the worst contracts in baseball. While the Red Sox wouldn't likely have much interest in the services of Alfonso Soriano or Milton Bradley with their salaries, Carlos Zambrano might intrigue Theo Epstein enough to initiate a conversation.
Zambrano has three years left on his contract at approximately $18 million per season. He has a vesting option for 2013, with the vesting based on Zambrano being among the Cy Young finalists in the next few years.
The Red Sox will have some work to do this winter, as they'll try to either keep or replace Jason Bay and begin a decision making process on veterans with options like Victor Martinez and Jason Varitek.
Would a trade of Zambrano for Papelbon and another arm make sense for the Red Sox and Cubs?
The Chicago Tribune has reported that the Cubs are having serious internal discussions about whether to offer an extension to Rich Harden. The rumors are that four years and between $50 million and $60 million are where the terms would land for Harden to stay in Chicago.
The Cubs also reportedly have interest in keeping their one 2009 All Star, Ted Lilly, after his contract expires after 2010.
By trading Zambrano for a closer like Papelbon, the Cubs would free up roughly $10 million per season over the next three years to spend on one or both of those arms, or another veteran free agent.
Meanwhile, the Red Sox would get a starter signed through 2012 as an insurance policy if they cannot, or will not, meet Beckett's demands.
With Clay Buchholz, Jon Lester, and Bard coming up through their system, there are arms for the Red Sox to restock with from inside their system.
But there's one more idea to consider: the Yankees.
New York added CC Sabathia and AJ Burnett to their rotation before this season, and the dividends of those enormous contracts could be a division title.
The Red Sox could be looking to make a similar impact on their own rotation for 2010, and putting Zambrano next to Lester and Beckett would certainly do that for Boston.
Now the money isn't even close between Papelbon and Zambrano. Papelbon is making less than $7 million after signing a deal to avoid arbitration in January, which is $11 million less than Zambrano will make next season. There would need to be either another player coming to Chicago, or cash headed to Boston.
But a trade of an ace that's fallen out of favor with many of his fans and a closer that appears to have fallen out of favor with some parts of his team's management might be a perfect change of scenery scenario for both players.