St. Louis Cardinals lefty Matthew Liberatore is a different story entirely. His 3.67 ERA in 2026 looks passable until you see the five home runs in 27.0 innings (1.67 HR/9) and the 10 walks. Then there is the history against Seattle. Liberatore has faced this lineup twice in his career and lasted a combined 1.2 innings, surrendering seven earned runs across those two starts. That is not a sample problem. That is a matchup problem. The Mariners have a working blueprint for getting to him, and the veterans in that lineup have seen him before.

Busch Stadium adds one more layer to the equation. Its park factor sits at 0.98 for runs and 0.95 for home runs, both tilting pitcher-friendly. That matters because the Cardinals' primary offensive weapon is power. They have hit 27 home runs as a team this season. Woo has not allowed one. Both lineups are operating below the league average offensively, Seattle at .223 and St. Louis at .230, which means the environment for scoring is already compressed before you factor in the mismatch on the mound.

Randy Arozarena is the player who ties it all together. He is 2-for-5 with a home run and a 1.333 OPS in six career plate appearances against Liberatore. His 2025 sample against the Cardinals lefty produced a 2.333 OPS. His OPS against left-handed pitching this season is .985, and he is carrying a .857 OPS over his last seven days. A right-handed bat who has torched this specific pitcher at every level of the data, facing a starter whose command issues create opportunities from the first at-bat. On the other side, Jordan Walker owns eight home runs and a .581 slugging percentage this season but has gone 0-for-2 with a 0.000 OPS in limited exposure against Woo, and his .427 OPS over the last seven days reflects a cold stretch at a difficult time to face an ace.

• Bryan Woo's zero home runs allowed in 32 innings is the defining number of this matchup. St. Louis leans heavily on power (27 HR this season), and that is precisely the weapon Woo has neutralized all year at a near-historic rate.
• Matthew Liberatore's career history against Seattle is alarming: 1.2 total innings across two starts, seven earned runs allowed. This is not a pitcher who has found answers against this lineup, and the Mariners know it.
• The Cardinals carry a -12 run differential at 14-11. Their 5-1 record in one-run games and 5-0 extra-innings mark are real, but they are outperforming their underlying production. That kind of gap tends to close over the second half of the season.
• Busch Stadium plays slightly pitcher-friendly (runs factor 0.98, HR factor 0.95). Two below-.230 lineups in this environment creates the conditions for a game that resolves well under the total.
• Arozarena is the most dangerous individual matchup on either roster. Career numbers against Liberatore (.400 AVG, 1.333 OPS, HR in 6 PA), a strong platoon advantage against a lefty, and a .857 OPS over the last seven days all point the same direction.
• Seattle is 2-8 on the road, a structural drag that is real and worth acknowledging. But road records are team-level averages, and Woo is not an average pitcher. The individual matchup advantage may be strong enough to override the split, particularly against a starter with Liberatore's Seattle history.

The Under 7.5 is the thinner play. It needs Woo to maintain his home run suppression, needs both lineups to keep doing what they have been doing offensively, and needs Busch Stadium to play to its profile. Those are reasonable conditions, not guarantees. The clearest single-player prop in this game is Arozarena over 0.5 hits: career matchup, platoon advantage, current form, all pointing the same direction against a starter he has historically dominated. If one bet in this game has the cleanest signal-to-noise ratio, that is it. The caveat on everything here is that Seattle's 2-8 road record is real, and Liberatore had a quality start in his most recent outing (6 IP, 1 ER vs Houston). Road records regress toward average over time, but they do not vanish overnight.

For the full slate, see our MLB picks today, NRFI picks, and player props.