How Kendrick's grand slam changed Nats' fortunes in 2019 playoffs

I had a question last week regarding the cWPA (change in World Series win probability) as it pertained to Howie Kendrick's grand slam in the top of the 10th inning in National League Division Series Game 5. Moving away from cWPA for a moment, I studied how The Baseball Gauge displayed the NLDS win probability for the entire series between the Nationals and the Dodgers last October, won by Washington, three games to two.

Prior to that 10th inning, the Nationals had better than a 50 percent chance of winning the series for just a short time: from the bottom of the ninth in Game 2 (48.4 percent) through most of the first six innings of Game 3.

With the Nats leading 2-1 in Game 3, Russell Martin's two-run double in the top of the sixth gave the Dodgers the lead back. That also allowed the Dodgers win probability for the series to jump from 41.1 percent to 55.2 percent.

The Nats' win probability never again reached at least 50 percent until late in Game 5, even though they had tied the series at two games apiece following their 6-1 win in Game 4. The Dodgers still enjoyed a 53.2 percent chance winning the series after Game 4 as both teams boarded charter flights back to Los Angeles for the final game of the series.

In Game 5, the Dodgers led 3-1 in the top of the eighth, enjoying a 87 percent chance of winning the series with ace Clayton Kershaw still pitching. Anthony Rendon crushed a solo homer to cut the lead to 3-2, and with it, the Dodgers' series clinching percentage went to 75.8 percent. Juan Soto was up next and his solo shot tied the game at 3-3. The Dodgers' win percentage fell over 22 percentage points to 53.2 percent.

Later in the game, the Dodgers' win probability actually returned to 53.2 percent with the game tied at 3-3 in the bottom of the ninth. Chris Taylor's lineout to center field with two away moved the needle from 59.2 percent chance of Dodgers winning the series to 53.2 percent.

Then the fun really began for the Nats.

In the top of the 10th, Adam Eaton drew a walk off of Dodgers reliever Joe Kelly. Suddenly the Nats were favored to win the series, as the win probability for the Dodgers dropped from 53.2 percent to 44.7 percent. Rendon's double with no one out put runners at second and third. The Dodgers' win percentage dropped again, this time from 44.7 percent to 19.6 percent. An intentional walk to Soto loaded the bases, and the win probability dropped another 1.7 percent to 17.9 percent.

Kendrick then stepped up and drilled Kelly's offering to deep right-center field and over the wall for a grand slam. No one out in the inning, and the Nats suddenly led 7-3. The Dodgers' winning percentage dropped to 1.7 percent. Or put in Nats terms, D.C.'s win percentage was a stunning 98.3 percent.

Go back to the top of the seventh when Kershaw struck out Eaton to end the frame. The Dodgers had the best potential to take the series at 89.3 percent in win probability.

In the span of five half-innings, that percentage went from 89.3 percent to 1.7 percent, thanks to the back-to-back solo homers by the Nats and Kendrick's grand slam. That is a drop of 87.6 percent.

A cataclysmic drop in win probability has happened to the Nats in the playoffs, too.

The most infamous was the Cardinals comeback in the 2012 NLDS. After Drew Storen struck out Allen Craig for the second out in the top of the ninth and with the Nats leading 7-5, Washington had a 96.6 percent chance of winning the series. A few batters later, yada-yada-yada, Pete Kozma's two-run single made it 9-7 Cardinals and the Nats' winning percentage had fallen to 8.4 percent.

But I don't need to remind anyone of that game, do I?

Kendrick's two monumental game-altering homers in the 2019 postseason sent seismic charges through the win probabilities of the Dodgers and Astros. Kendrick's grand slam in the NLDS was part of a 10th inning that watched the Nats' chances to win series jump from 46.8 percent to 98.3 percent. Singlehandedly in Houston, Kendrick's blast that clanged off the right field foul pole lifted the Nats almost 35 percentage points in their World Series win probability.

But a deeper dive into the changes in World Series Win Probability (cWPA) in Nats playoff history shows that Rendon's double in the top of the 10th in NLDS Game 5 was actually the top-rated cWPA, rather than Kendrick's grand slam. Rendon's hit to put two men in scoring position with the game tied held a cWPA of .063, while Kendrick's grand slam two batters later posted a cWPA of .040. The Kendrick hit ranked as No. 11 all-time Nats postseason history.

There are some gems on this list: Jayson Werth's homer to win game 4 of the 2012 NLDS is ranked sixth (.045 cWPA), Soto's 2019 NLDS Game 5 homer is on this list (.057), Chris Heisey's two-run shot in Game 3 of the 2016 NLDS and even Tyler Moore's single to win NLDS Game 1 in 2012 make the top 10.

The list also includes negative plays too, so the cWPA algorithm works both ways.

Next up? How about a probability deep dive into that eighth-inning comeback against the Brewers in the wild card game?