Mike Petriello (MLB.com) reports that Yordan Alvarez's ninth-inning, game-winning three-run homer, which gave the Astros an 8-7 win over the Mariners on Tuesday in ALDS Game 1, "the most valuable postseason moment a position player has ever had", as measured by Win Probability Added.
When Alvarez stepped to the plate in the ninth inning, Seattle's win probability was 91%. That's based on the history of road teams who were ahead by two runs with two outs and two on in the ninth inning, as the Mariners were. . . .
If Seattle's odds were 91% when the pitch left Robbie Ray's hand, then by the time Alvarez's blast landed 438 feet away, their odds of winning were 0%, because the game was over.