Five times that the rain played a major role in shaping postseason history

Game 4 of the National League Division Series between the Cubs and Nationals was postponed due to rain on Tuesday. Wrigley Field looked majestic but not very playable:

The teams will square off at 4 p.m. ET on Wednesday on TBS instead. Will it give the Nats a chance to get some more rest? Will the Cubs lose the momentum they had following their Game 3 victory? Of course, this is far from the only time that rain has had a hand in determining the course of the postseason -- because even the best teams get a little assist from Mother Nature sometimes.
Game 7, 2016 World Series
The Cubs were reeling a bit. After jumping ahead early in Game 7, Chicago took a 6-3 lead into the bottom of the eighth, just six outs away from finally ending that 108-year World Series drought -- only to watch it disappear on Rajai Davis' game-tying two-run homer. As the game went into extra innings, the old doubts started creeping back in: Was the Curse of the Billy Goat rearing its head again?
And then the rain came.

While the rest of the baseball world eagerly waited for the game to resume, the Cubs took the 17-minute delay to regroup -- thanks to a rousing clubhouse speech from Jason Heyward.
"I told them I love them," Heyward told MLB.com after the game. "I told them I'm proud of the way they overcame everything together. I told them everyone has to look in the mirror, and know everyone contributed to this season and to where we are at this point. I said, 'I don't know how it's going to happen, how we're going to do it, but let's go out and try to get a W.'"
As you've no doubt heard by now, Chicago did do it. Immediately after play resumed, Kyle Schwarber led off the 10th with a single, and pinch-runner Albert Almora Jr. came around to score the winning run on a Ben Zobrist double.

Game 4, 2006 World Series
Having already dealt with rain in the NLCS, the 2006 Cardinals got another round of wet stuff for the World Series against the Tigers. Game 4 was washed out and thus delayed by a day, meaning that Game 5 was pushed back as well. Already down 2-1 in the Series, the rain made Craig Monroe even more sad:

Game 4 fit the pattern of the '06 Series, a close Classic game-wise won by the Cards where an error by a pitcher loomed large (you may recall the Fernando Rodneythrowing error on a So Taguchi bunt). St. Louis went on to end the Series at home the next night, with Adam Wainwright closing out the WS for the third time in as many rounds. 

Game 5, 2008 World Series
In the 105-year history of the Fall Classic, a game had never been suspended due to rain -- until 2008.
The Phillies and Rays had already sat through a 90-minute delay in Game 3, and another ominous forecast loomed for Game 5. With Philadelphia just one win away from its first World Series championship in nearly 30 years, though, the game began as scheduled.
And for the first few innings, it seemed like it might work. Mother Nature, however, had other ideas:

The rain started falling hard in the fourth, and eventually it became difficult for the grounds crew to keep pace -- in the words of Chase Utley, "the infield was basically under water." So, with the score tied at 2 in the sixth, the umpires and Commissioner Bud Selig were left with no choice: The game was suspended, and due to more inclement weather the next day, it would be nearly 49 hours until the teams resumed play.
Once they did, it didn't take long for the fireworks to start. Jayson Werth gave the Phillies the lead in the sixth, and after Rocco Baldelli answered with a solo homer for Tampa Bay, Pedro Feliz drove in Eric Bruntlett to put Philly in front, 4-3. From there, it was all Brad Lidge:

Game 7, 1925 World Series
In the biggest game of the season, the Senators and Pirates didn't just get rain -- they got quite possibly the worst playing conditions in World Series history. 
Game 7 was postponed due to rain, but with no end to the downpour in sight, the teams decided to go ahead and make the best of things the next day. What followed was almost beyond belief: standing water everywhere, fog so thick that outfielders weren't visible from the press box, so much mud that legendary Senators starter Walter Johnson had groundskeepers apply sawdust to the mound multiple times.

Despite Johnson's struggles, though, Washington still took a 6-4 lead into the bottom of the seventh -- at which point the rain had one more trick up its sleeve. After an error put the leadoff man on second base, Pirates center fielder Max Carey hit a line drive right down the left-field line. The ball was ruled fair, trimming the Senators lead to 6-5, but left fielder Goose Goslin argued that the ball had actually landed in foul territory. His proof? The ball was still stuck in the mud.
Alas, the call on the field stood, and Pittsburgh scored one more in the seventh and three in the eighth en route to a 9-7 win.
Game 7, 1986 World Series
Everybody remembers the rally and the error in Game 6, but that was just to keep the Mets alive -- there was still a Game 7 left to be played, and some inclement weather in New York provided one of baseball history's great what-ifs.
Game 7 was originally scheduled for Sunday, Oct. 26, the day after Game 6, but rain pushed it back a day. That allowed Red Sox manager John McNamara, who'd planned on starting Oil Can Boyd, to instead roll with Game 5 starter Bruce Hurst on three days' rest. At first, it seemed like the call would pay off: Boston jumped on Ron Darling early and took a 3-0 lead into the sixth.
That is, until Hurst -- who threw a jaw-dropping 130 pitches in Game 5 and hadn't pitched on short rest all year -- was allowed to come back out for the sixth.

Three hits, a walk and an RBI groundout later, New York had tied things up. They'd add three more runs in the seventh and go on to take the World Series with an 8-5 win. Which begs the question: Had Game 7 been played as scheduled, would things have worked out the same way?