Expect the Unexpected: WE and WPA

"May the odds be ever in your favor!" Effie Trinket beseeches the tributes at the outset of The Hunger Games, giving hope to competitors everywhere that such a thing might, in fact, be plausible. But every opponent in a head-to-head competition knows full well that each contest begins the same way: with the odds equally locked at 50-50.
The 2016 World Series proved no different. It pitted two teams -- the Indians and Cubs -- battling to overcome longstanding title droughts, of 68 and 108 years, respectively. And although each fanbase wanted to believe that its club was destined to take home the trophy, Baseball-Reference's Win Expectancy (WE) calculation indicated otherwise. At 7:10 p.m. CT on Oct. 25, 2016, the combatants trotted onto Cleveland's Progressive Field with an equal chance at achieving the impossible.
Throughout the Series' seven games, across the 55 innings peppered with 54 runs scored, the momentum ebbed and flowed, leaving all those watching on the edge of their seats. Let's relive the drama and suspense by analyzing the defining moments from the 2016 World Series according to Win Probability Added (WPA), which measures the impact that a single play has on a team's win expectancy.
GAME 1
Indians 6, Cubs 0
Defining Moment: José Ramírez's first-inning RBI single; .09 WPA
Ace Corey Kluber opened the Series on his home turf by getting Dexter Fowler to strike out looking, upping the Indians' win expectancy from 50 to 52 percent. From that point on, Cleveland would maintain the upper hand. Ramirez boosted the home team's chances by 9 percent with an RBI single in the bottom of the first, and Brandon Guyer, the very next batter, helped bring his club's WE to 74 percent when he was hit by a Jon Lester pitch with the bases loaded.
Although it might seem presumptuous to hang a team's fate on first-inning performance, Lester, who took the loss, conceded its importance. "The first inning was tonight's game," he said. 
In the bottom of the eighth, Roberto Pérez put the nail in the Cubs' metaphorical coffin with a three-run homer off Héctor Rondón, giving Chicago a zero mathematical chance at a comeback. 
GAME 2
Cubs 5, Indians 1
Defining Moment: Ben Zobrist's fifth-inning RBI triple; .11 WPA
The Cubs began Game 2 with a fresh slate, and they didn't waste the opportunity, getting on the board in just their third at-bat of the game, via an Anthony Rizzo RBI double. 
"It's nice to score first, especially when you're the visiting team," said Kris Bryant, who came home on the play. "Take the momentum away. To get up there and score within the first three batters is huge." 
The run brought Chicago's win expectancy to 61 percent, but according to the data, that wasn't even the most impactful play of the game. Rizzo reached base again in the fifth, this time via a walk, and Zobrist promptly brought him home with a triple to right. Then Kyle Schwarber, who had missed all but two regular-season games to injury, knocked his second RBI single of the evening to help put the game away. 
When Addison Russell drew a bases loaded walk four batters later, it brought the Cubs' chance of victory to 93 percent. And although the home team got on the board in the sixth, it barely moved the needle on the WE scale, as Chicago went on to even the Series at a game apiece.

GAME 3
Indians 1, Cubs 0
Defining Moment: Cody Allen's game-ending K of Javier Báez; .24 WPA
Game 3 at Wrigley Field was the first of three contests in the 2016 Fall Classic that would ultimately be decided by a one-run margin. And Cleveland didn't even plate its lone run until the seventh, when Manager Terry Francona tabbed Coco Crisp to pinch-hit for Andrew Miller, who had tossed 1.1 frames in relief at that point. Crisp delivered in the clutch, and although his RBI single off Cubs reliever Carl Edwards Jr. was worth just 5 percent WPA, it gave the visiting team the upper hand in enemy territory. 
Still, the Cubs clung to hope for a victory -- threatening with a Jorge Soler triple in the seventh and two base runners in the bottom of the ninth -- until the very last batter. When Allen got Baez to strike out swinging with the winning run on second base, it closed the book on the game and what would be Allen's only save of the Series.
GAME 4
Indians 7, Cubs 2
Defining Moments: Carlos Santana's second-inning HR, Corey Kluber's second-inning RBI single; .11 WPA (tied)
When Anthony Rizzo knocked in Dexter Fowler to put the Cubs on the board in the bottom of the first, it seemed as though the home team might be in control of its fate. But the advantage proved to be short-lived, as Cleveland capitalized on two Kris Bryant errors in the second to claim a lead it wouldn't relinquish. Santana led off the inning with a game-tying solo shot off John Lackey, before Bryant's first throwing error, a fielder's choice and an intentional walk set the stage for Kluber. Cleveland's ace helped his own cause with a dribbler down the third-base line, on which Bryant made another errant throw, allowing Lonnie Chisenhall to score the go-ahead run. The Indians continued to increase their win expectancy with runs in the third, sixth and seventh, but no inning was more impactful for them than the second.
GAME 5
Cubs 3, Indians 2
Defining Moment: Kris Bryant's fourth-inning HR; .14 WPA
Following the Cubs' Game 4 loss, which gave the Indians a two-game advantage, Bryant assessed the stakes. "We know we've got to win out," said the third baseman. "But we've won three games in a row plenty of times. It can be done easily."
And so, Bryant took it upon himself to avenge his pair of Game 4 errors and deliver the home run that arguably turned the tide of the entire Series, propelling Chicago to three straight victories. With Cleveland up, 1-0, courtesy of a Jose Ramirez solo homer, Bryant catalyzed a rally by launching a longball of his own to lead off the bottom of the fourth. An Addison Russell RBI single and David Ross sac fly later, and the Cubs had tallied a .34 WPA in the fourth alone, increasing their win expectancy from 42 to 76 percent. 
Cleveland tacked on another run in the sixth, but Chicago hung on to begin its slow climb to the top. 
GAME 6
Cubs 9, Indians 3
Defining Moment: Addison Russell's first-inning RBI double; .15 WPA
The Cubs struck early when the Series returned to Progressive Field for what would be the penultimate contest. Game 5 hero Kris Bryant stepped up again, giving Chicago a 1-0 edge when he went yard with two outs in the first. Back-to-back singles followed, putting the spotlight on Russell. He made Indians starter Josh Tomlin pay by knocking a two-run double to center -- arguably a catchable ball -- giving the Cubs a 75 percent win expectancy before the top of the first was through. 
Surprisingly, it was that double, and not the grand slam he'd launch in the third, that proved more mathematically meaningful for Russell. Again facing Tomlin, he smashed a 434-foot shot, virtually assuring that there would be a Game 7. 
"That was the hit of the night," said Bryant. "Any time you get four runs on one swing, [that's] huge."
Overall, Russell totaled a .254 WPA for the night, far better than any other single player on the field.
GAME 7
Cubs 8, Indians 7
Defining Moment: Ben Zobrist's game-winning RBI double; .31 WPA 
Of all the games in this Series, the seventh and final contest exemplified the "anyone's got a shot" attitude. The lead changed hands five times over 10 frames, and as if that wasn't enough of an emotional roller coaster for the players and their fans, rain stopped the affair for 17 minutes after extra innings had become a certainty. 
The Cubs had to be confident when the very first batter of the evening, Dexter Fowler, blasted a 2-1 pitch over the Progressive Field wall. But in the third, Carlos Santana's RBI single evened the score. Addison Russell and Willson Contreras used their hot sticks to swing the momentum back in Chicago's favor in the fourth, combining for a 13 percent WPA, before Javy Baez and Anthony Rizzo gave their club an 88 percent shot at taking home the trophy with a home run and an RBI single, respectively, in the fifth. 

The pendulum, however, didn't stop swinging there. When reliever Aroldis Chapman took the mound in the eighth to face the Indians' 6-7-8 hitters, the Curse of the Billy Goat seemed all but erased. But Chapman surrendered an RBI double and a Rajai Davis two-run homer to tie the game, in the process decreasing the Cubs' win expectancy from 94 to 47 percent. The Cubs threatened in the top of the ninth, stranding a runner on third, but extras were ordered when neither club could break the stalemate. Following the rain delay, the teams were back where they started -- peering down a 50-50 shot at victory -- when the 10th inning opened. 
Four batters in, Zobrist connected for the RBI double that would put Chicago back on top and earn him the World Series MVP Award, thanks to a .31 WPA on the play. "This one about made me pass out," Zobrist said when the dust cleared. "I feel like the way the Series was up and down, then getting up early in Game 7, then it getting away in the eighth, then scoring two in the 10th, it was an epic battle."