The St. Louis Cardinals defeated the Washington Nationals 6-3 at Roger Dean Chevrolet Stadium on March 15, 2026, handing Washington a loss that was reflected in the DiamondIQ model's estimate moving from a 64 percent pre-game home win probability all the way to 100 percent by the final out. St. Louis built its advantage in layers, with the Cardinals striking first in the bottom of the first inning when Nelson Velázquez connected on a home run off Miles Mikolas, a swing that added 6.0 percent to St. Louis's win probability. Washington briefly threatened to seize control in the top of the second when Joey Wiemer launched a home run off Hunter Hayes, a hit worth plus 11.7 percent win probability for the Nationals, but that momentum proved short-lived as Cardinals pitching systematically shut down Washington's offense over the following innings.
The Nationals repeatedly stalled at critical moments, with two double plays proving particularly damaging. In the top of the sixth, Luis García Jr. grounded into a double play off Ryne Stanek that cost Washington 7.0 percent in win probability, and Nasim Nuñez followed with a similar outcome in the top of the seventh against JoJo Romero, draining another 7.8 percent. St. Louis added an insurance run in the bottom of the eighth on a Washington fielding error, a miscue that added 6.2 percent to the Cardinals' probability. Washington finished with four errors on the night against just one for St. Louis, and the Nationals managed only five hits across nine innings.
On the pitching side, Richard Fitts was the model's highest-valued arm with plus 15.3 percent win probability added, followed by Riley O'Brien at plus 8.1 percent and JoJo Romero at plus 7.2 percent, collectively anchoring a Cardinals staff that held Washington largely in check after the second inning. Among position players, Joey Wiemer led Washington with plus 8.6 percent WPA and a RE24 of plus 2.4, while Nelson Velázquez paced St. Louis at plus 6.4 percent WPA and plus 2.5 RE24. The DiamondIQ model leans toward crediting St. Louis's pitching depth and Washington's defensive miscues as the primary drivers of the Cardinals' comfortable final margin.
Analysis generated by DiamondIQ's model.