For days, sources across the Major Leagues noted a spike in trade activity throughout the industry.
Monday, we saw tangible evidence with the Yankees' acquisition of James Paxton.
• Latest MLB free agent and trade rumors
With Thanksgiving Day fast approaching, the heart of the baseball offseason is here. Based on initial readings from the Hot Stove, here are the key storylines to follow during the holiday weekend:
1. The Mariners aren't done dealing.
Almost certainly, the Paxton trade wasn't the last significant move Seattle general manager Jerry Dipoto will make this winter.
The Yankees also asked Dipoto about shortstop Jean Segura, who is available for the right price. The Phillies also have interest in Segura, who is known for his bat control and could help a Philadelphia lineup that finished third in the Majors with 1,520 strikeouts this year.
As first reported by MLB Network insider Ken Rosenthal, the Mariners have spoken with the Padres about a trade that would send Segura and Mike Leake to San Diego in exchange for William Myers.
Perhaps most intriguingly, the Mariners haven't ruled out the possibility of trading Edwin Diaz. The Phillies and Braves are among the teams interested in Diaz coming off his 57-save season.
2. The Phillies are going to spend.
Perhaps you've heard about this.
"This is a franchise that's carried big payrolls for a lot of years," Phillies GM Matt Klentak told me during the General Managers Meetings. "It's no secret to you, or to me, or to the fans, or to the agents. Everybody knows that. It's always been a matter of when -- and not if -- the Phillies were going to spend again."

We know the Phillies have interest in signing Bryce Harper, Manny Machado ... and possibly even both. But they're also involved in the free-agent pitching market, showing interest in the top available starter (Patrick Corbin) and closer (Craig Kimbrel). As owner John Middleton told USA Today recently, "We're going into this expecting to spend money, and maybe even be a little bit stupid about it.''
As for the much-publicized link between Machado and members of the Phillies front office, Klentak said he had "pretty minimal" interaction with Machado while both were with the Orioles. Klentak left the organization to become assistant general manager of the Angels following the 2011 season, roughly 17 months after Baltimore selected Machado in the first round of the MLB Draft.
3. The catching market is moving.
Mike Zunino is a Ray. Jeff Mathis will be a Ranger. Kurt Suzuki is a National.
While patience is the watchword for the rest of the marketplace, catchers have begun changing teams. Suzuki's deal with the Nationals is especially consequential, as it appears to have eliminated Washington as a possible destination for free agents Yasmani Grandal and Wilson Ramos, as well as perpetual trade candidate J.T. Realmuto.

The Dodgers appear destined to acquire a frontline catcher and have interest in Realmuto. The same can be said for their 2017 World Series opponents in Houston.
4. Corbin is the top pitcher available. He probably won't sign first.
Every year, industry observers wonder if the No. 1 free-agent starter will set the market's upper boundary by signing early. That's not likely to happen with Corbin this autumn.
Two teams with significant capacity to add payroll -- the Phillies and White Sox -- have interest in Corbin. But they're also involved in the Harper and Machado pursuits, meaning they may wait for the superstar position players to go off the board before determining exactly how much they can spend on Corbin.

Meanwhile, the markets for Nathan Eovaldi and J.A. Happ are developing more rapidly. The Yankees, Blue Jays, Angels, Brewers, Phillies and Astros are among the teams known to have interest in Happ, sources say.
5. The D-backs' approach will be clear soon.
After weeks of speculation, the D-backs are about to show the industry how willing they are to trade veterans Paul Goldschmidt, Zack Greinke, Robbie Ray and Jake Lamb.
One source said the D-backs are confident they won't need to include cash in order to move Greinke's contract, on which three years and more than $90 million remain. Therefore, the Phillies -- everyone's favorite large-market spender -- are among the most logical suitors, if they don't sign Corbin.
Meanwhile, one source confirmed that the Twins and D-backs had preliminary discussions about a Goldschmidt trade at the General Managers Meetings. Those talks have not advanced, however, and MLB Network insider Ken Rosenthal reported the Astros and Cardinals have been most heavily involved in the Goldschmidt negotiations thus far.

6. The White Sox and Padres are ready to pounce.
One rule of the Hot Stove: Pay close attention to teams emerging from lengthy rebuilding efforts.
The White Sox are the American League's answer to the Phillies. While their roster isn't as strong (yet) as that of Philadelphia, they play in a winnable division and could compete in the next couple seasons if they land Harper, Machado, Corbin or lefty Dallas Keuchel. If the Indians trade Corey Kluber or Carlos Carrasco -- and industry opinion remains divided as to whether they actually will -- White Sox GM Rick Hahn has even more incentive to make bold moves.
Meanwhile, Padres general manager A.J. Preller said this month that his most likely approach this offseason will be to "stay the path" with the team's youthful core. But he also acknowledged the search for pitching "will always be part of the discussion," and reports have linked the Padres to trade discussions for Mets right-hander Noah Syndergaard.

William Myers is one name to watch in the days ahead. The Padres are willing to trade him, as evidenced by their talks with the Mariners, because they have a sudden abundance of young outfielders and Eric Hosmer at first base. If the Padres keep Myers, Preller has said he hopes to give him direction on where he's going to play defensively by the end of the Winter Meetings. If talks with the Mariners fail to produce a deal involving Myers, another option would be to trade a young outfielder -- such as Hunter Renfroe or Franmil Reyes -- elsewhere in a move that brings a pitcher to San Diego.
7. For Harper and Machado, the wait continues.
Harper and Machado are unlikely to sign with new teams until the Winter Meetings -- at the absolute earliest.
Scott Boras, who represents Harper, is known for continuing free-agent negotiations well into the New Year. Of course, Harper is a proud Las Vegas native. The possibility of an extravagant announcement in his hometown during next month's Winter Meetings may be too much for Hot Stove choreographers to resist.

The fascination with Harper could obscure the rest of the outfield market, with quality free agents Michael Brantley and A.J. Pollock remaining available for the time being. Their representatives may opt to wait until Harper signs and then pursue agreements with teams that fall short in the bidding. But that is likely to require some patience.