Headed toward a potentially epic October, the best teams in the National League don't just march on. They get better.
The Cubs, Giants and Nationals all improved at the non-waiver Trade Deadline, and it's no coincidence. They're on pace to win 94-99 games each, and all three are confident they're going to reach the postseason and have a crack to reach the World Series. But to win the NL pennant, they're going to have to survive one -- and maybe two -- short series against each other.
Now let's say Clayton Kershaw's back gets healthy and he heads into October on a late roll, with newcomer Rich Hill working behind him. Or the Cardinals, with their long history of outplaying expectations in the postseason, wind up reaching the NL Division Series. Maybe the Mets or Pirates hit their stride in September.
Now -- with apologies to the Rangers, Indians and everyone else in the American League -- the Cubs, Giants and Nationals will face major threats to their survival in every round of competition between the game's best teams.
We're heading toward the most delicious set of postseason series in one league since, well, forever. These teams are loaded, well managed and certain to be prepared. Don't be surprised if both series in the NLDS go to a decisive fifth game and the NL Championship Series goes seven.
That's why the strongest teams in the game viewed it as critical to improve. The Rangers and Indians may have upgraded the most at the Deadline, as most analysts concluded when the dust cleared on Monday, but it was fascinating to watch the best teams in the NL prepare to face each other.
Theo Epstein was speaking only for himself, but he voiced some universal sentiments in explaining why he paid heavily to upgrade the Cubs.

"It shows a lot of faith in our big league club,'' Epstein said after trading for closer Aroldis Chapman. "We said when we first got here that every chance to win is sacred, and we believe that. You can't take for granted the position we're in right now. … [Players] have worked their tail off to build up this nice lead heading into the stretch. We believe in these guys. We believe we have a chance to do something special, but there's a lot of work ahead.''
In a seller's market, the price for the pitching moves that the Cubs, Giants and Nationals all made was high. Epstein is a huge believer in 19-year-old shortstop Gleyber Torres, who headlined the deal to get Chapman from the Yankees, but he won't second-guess himself for playing that card.
"It was tough to give up what we gave up,'' Epstein said. "But if not now, when?''
Strong starting pitching is the common denominator between the Cubs, Nationals and Giants. That's viewed as the most essential ingredient for postseason success, as the quality of pitching and defense -- along with an ability to use top pitchers more than in the regular season -- often leads to tight, low-scoring games.
If they have six or seven pitchers who can carry it, a team can go a long, long way.
The Cubs are driven by MVP candidates Anthony Rizzo and Kris Bryant, and have a deep, versatile lineup. Their weakness was in the bullpen, and Epstein seemingly turned it into a strength by adding not just Chapman but also potential setup men from both sides in Joe Smith and Mike Montgomery. They follow Joe Nathan, making his comeback, into Wrigley Field.
Epstein calls Chapman a "game-changing type pitcher,'' and he's right. Epstein moved quickly to pull off a trade on July 25, because he knew that if he didn't grab Chapman, the Nats surely would. Dusty Baker managed him in Cincinnati and would have loved a reunion.

Nationals GM Mike Rizzo knew he had to do something, as Jonathan Papelbon had been allowing almost two baserunners per nine innings for the past month, but he didn't want to sacrifice the top prospects it would have taken for Chapman or Andrew Miller, whom the Yanks dealt to the Tribe. Instead, Rizzo plucked rent-a-closer Mark Melancon from the Pirates in a deal that cost him lefty reliever Felipe Rivero and a second-tier prospect in 21-year-old right-hander Taylor Hearn.
Melancon is a strong addition for a team (and a manager) that has had a run of untimely blown saves in postseason games. Rizzo believes he has the right stuff, and he's right.
"He's a known commodity, and he's a successful late-inning reliever and a guy we had followed for years,'' Rizzo said. "A good makeup guy. Battle tested and one of the elite relievers in the game."
Never mind that Melancon's fastball averages 91.9 mph, not 100.9 like Chapman. Melancon throws 89 percent cutters and curveballs, and he has used that mix to convert 81 of 86 save chances the past two seasons.

Giants executive VP for baseball operations Brian Sabean and GM Bobby Evans felt the need to add depth to both the rotation and bullpen. They did that by adding lefties Matt Moore from the Rays and Will Smith from the Brewers.
San Francisco had previously added All-Star infielder Eduardo Núñez from Minnesota, which allowed the Giants to include their top third baseman, Matt Duffy, in the deal to get Moore.
Moore will work behind Madison Bumgarner and Johnny Cueto in a starting rotation in which $90 million free agent Jeff Samardzija could be bumped into the role of No. 4 starter. Smith assumes an important bullpen role alongside fellow lefty -- and proven October weapon --- Javier López.
These weren't easy deals for the Giants to make, as top pitching prospect Phil Bickford went to the Brewers and highly regarded infielder Lucius Fox was included in the package to get Moore from the Rays. But October is coming fast and the bar for NL teams to clear this year will be extremely high.
"We have to finish strong and make sure we get into the postseason,'' said Epstein, who doesn't want to take the Cards and Bucs for granted. "Then the goal is to win three postseason series. That's not an easy thing to do.''
Especially against this competition.