“They showed him in the dugout, and his face just said it all,” Martinez said. “He’s like, he felt like he let the team down. And for him to come back and do what he’s done in this series and hit that grand slam in L.A., that only tells you what kind of person, what kind of player, he is.”

Kendrick, who at 36 has finally reached his first World Series after 14th major league seasons, is one of several players over 30 who have turned the latter stages of the postseason into an exhibition of the value of veterans. The three remaining teams — the Nationals, Yankees and Houston Astros — were in the top four for the oldest average roster age this year, and the other N.L.C.S. team, the Cardinals, was the sixth oldest.

The Nationals led all teams at an average age of 30.1 years — a number skewed a tad by the presence of the 42-year-old reliever Fernando Rodney — and the Yankees were second at 30.0, according to ESPN’s roster analysis. As Sarah Langs of M.L.B. noted, Kendrick is tied as the third-oldest position player to become a league championship M.V.P.

Much of Kendrick’s career has been about comebacks, which, in a way, makes him the consummate 2019 Washington National, because the club came back from a 19-31 start to the season to win the National League pennant.