The other arm in this matchup is where the story gets complicated. Kyle Leahy has been a reliable piece for the St. Louis Cardinals all year, finishing with a 10-4 record and a 3.33 ERA across 135.0 innings. But his last three starts lasted 3.0 innings, 2.2 innings, and 3.0 innings. That is 8.2 combined innings. Whatever is behind that pattern, the practical result is the same: St. Louis is handing this game to their bullpen before the fifth inning arrives. A Cardinals relief corps with a 4.01 ERA is absorbing the bulk of the load against a Nationals lineup scoring 5.1 runs per game. The Leahy of the September ERA is not the Leahy showing up in tonight's box score.

The Cardinals enter this series opener having dropped two straight to San Francisco, sitting 75-78. Their offense is .242 with a .698 OPS this season. Against right-handed pitching, they are 49-57. Cavalli is a right-handed pitcher. Báez, St. Louis's rookie outfielder, is day-to-day with left side tightness after exiting Wednesday's game. As beat writer Derrick Goold reported, "Joshua Baez left Wednesday's game against the Giants with tightness in his side." If he misses tonight's start, Nathan Church and Victor Scott II fill out the outfield corners. Church is a .252 hitter this season. Scott carries a .469 OPS against right-handed pitching, which is among the weakest marks in St. Louis's lineup depth chart.

Washington brings Daylen Lile, CJ Abrams, and James Wood against a Leahy who has allowed 14 home runs in 135.0 innings this season. Lile is posting a 1.042 OPS over his last seven days. Wood has 30 home runs and a .957 OPS against right-handed pitching. In tonight's MLB action, the pitching mismatch is as clear as it gets at this point of the season. One confirmed ace. One starter with a pattern that raises serious questions about his workload. Everything flows from that gap.

• Cavalli has posted 9, 8, and 8 strikeouts in his last three consecutive starts, clearing the 6.5-strikeout line each time. Against a Cardinals lineup that is 49-57 vs right-handed pitching with a .698 OPS, his strikeout floor looks well-established entering tonight.
• Leahy's last three outings total only 8.2 innings pitched (3.0 IP, 2.2 IP, 3.0 IP). If that pattern continues, St. Louis's 3.33 season ERA becomes irrelevant by the fourth inning and the Cardinals are effectively running a bullpen game from the start.
• The Báez left side injury is the Cardinals' most meaningful lineup uncertainty. If he cannot go, Nathan Church and Victor Scott II fill the outfield corners. Scott's .469 OPS vs right-handed pitching is the thinnest contact profile Cavalli could face in any starting role tonight.
• Busch Stadium plays pitcher-friendly, with a runs factor of 0.98 and a home run factor of 0.95. The park context reinforces an Under lean on the total, particularly with an elite strikeout pitcher working the first six or more innings for Washington.
• Washington is the contrarian side here. Cavalli is the clearly superior starter, yet the Cardinals are priced at -128 primarily on home field. The market is weighting venue over pitching quality. That mispricing is the foundation of the Nationals moneyline and run line cases.
• JJ Wetherholt returned to the Cardinals lineup this week but is in an offensive freeze. His last 7-day OPS is 0.000, and his career numbers against Cavalli (all 2026) show 3 PA, .000 AVG, and a 0.333 OPS. He bats into a strikeout pitcher with no current mechanical answers and a poor specific track record against this arm.

The Nationals moneyline at -116 and the run line at +116 represent genuine contrarian value when the pitching gap is weighted correctly over venue alone. The Under at 7.5 carries the least conviction of the three core picks. Cavalli suppresses St. Louis's scoring. The uncertainty is entirely around Leahy's side, and early bullpen exposure against a Washington offense averaging 5.1 runs per game is real blowback risk. LOW confidence on the Under is the honest positioning. For the best single-bet play on this slate, the Cavalli strikeout over at +102 is the one you want in front of you when the final out is recorded.

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