Shortly after Tuesday’s trade deadline, something happened that could more significantly impact the rest of the season than the San Diego Padres’ blockbuster acquisitions: Jacob deGrom returned to the mound for the New York Mets.

While the Mets had a quiet deadline, deGrom could be the greatest second-half addition in the majors if he picks up again as the game’s best pitcher.

DeGrom missed the season’s first four months following a stress reaction in his right scapula during spring training. In his first major-league appearance since July 7, 2021, he allowed a run and three hits over five innings, with six strikeouts and no walks. Perhaps the Mets’ cautious approach to his recovery will pay off; many pitchers with stress reactions have returned much sooner. But deGrom also missed the last three months of the 2021 season with a right elbow strain that didn’t require surgery.

He looked like his old self Tuesday. His average fastball velocity, which remarkably keeps rising in his 30s, reached 99.8 mph. He hit 102 mph in the first inning against Victor Robles. According to Statcast, he threw 13 pitches at 100 mph or better.

With deGrom’s return, along with Max Scherzer’s last month, the Mets have the potential for the best playoff rotation in the National League, especially as fifth starters are shed and fourth starters are used as sparingly as possible.

The Padres’ acquisitions of Juan Soto, Josh Bell, and Josh Hader make them a likely wild-card team that no division winner will want to face. The defending champion Atlanta Braves improved their bullpen and have Ronald Acuna back on the field. In Milwaukee, the Brewers’ playoff chances at FanGraphs dipped by just 1.3% after trading quality (Hader) for quantity and additional years of control. And the Los Angeles Dodgers, even after a quiet deadline, are a World Series-winning threat, if not the favorite.

There’s never been a deadline trade acquisition as young and talented as Juan Soto. Denis Poroy / Getty Images Sport / Getty

It all means this is shaping up to be the most compelling NL playoff chase of the last decade.

Since 2014 – the first year of FanGraphs’ archive of playoff probabilities – there’s never been a season in which four NL teams enjoyed World Series-winning odds of 8% or better as late as Aug. 4.

The Dodgers, Mets, Braves, and Padres all enjoy such odds, which is indicative of their excellent rosters and potentially balanced playoff matchups. They’re made more impressive as the field is actually diluted with an additional wild card this year. All four teams have a 96% or better chance to make the playoffs.

The only other time there were as many quality contenders in one league with 8% of better chances by Aug. 4 was in the 2018 AL field. That year, the top two teams met in the ALCS, when the Houston Astros faced the Boston Red Sox, who went on to win the World Series. The New York Yankees and Cleveland were the other two contenders.

Last year, only one NL team had greater than an 8% World Series-winning probability on Aug. 4: the Dodgers, overwhelming favorites at 22%. The Braves were in the beginning stages of their second-half tear and owned a probability of just 1.4%. It’s a reminder that baseball is difficult to forecast and anything can happen in the small sample of the postseason.

Even after a quiet deadline, Trea Turner and the Dodgers still might be NL favorites. Matthew Stockman / Getty Images Sport / Getty

The new postseason format this year adds another layer of intrigue, with an additional wild card added in each league and the two top division winners receiving first-round byes.

The Dodgers enjoy an overwhelming 96.5% probability to win the NL West despite the Padres’ moves, while the Mets hold a 73.7% chance and a 3 1/2-game lead over the Braves. They’re the most likely to earn the first-round byes. The Dodgers hold a five-game edge over the Mets entering play Thursday.

While the division winner with the best record claims the top seed, the No. 2 seed might be the more favorable spot this fall. The No. 1 seed will face the winner of the first-round series between the top two wild-card teams, which could very well be a matchup between the Padres and Braves. The Dodgers’ reward if they retain the best record could thus be a meeting against a lineup with Soto, Manny Machado, and Fernado Tatis Jr., or a clash with the reigning World Series champions. The strengthening of the NL field at the deadline is one reason why the Dodgers’ playoff chances declined right after.

The Padres’ World Series chances increased by 3.5% after the deadline, according to the ZiPS forecast at FanGraphs, while the Dodgers’ chances declined by 3.1%.

Ronald Acuna Jr. is back this year after missing the Braves’ World Series run following a knee injury. Sean M. Haffey / Getty Images Sport / Getty

The No. 2 seed will likely face the winner of the first-round series between the NL Central champ and the weakest wild card. It’s a more favorable matchup.

Perhaps the field ought to be seeded by record or have reseeding after the first round to provide more of a benefit to those clubs with the best regular-season resumes.

Much is still to be determined, but this week’s events have created the possibility of an NL postseason unlike any other in recent memory.

Travis Sawchik is theScore’s senior baseball writer.

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