Arizona Diamondbacks vs. Seattle Mariners

Platform comparison

Active sub-markets

Market context

The Arizona Diamondbacks travel to Seattle for a regular-season matchup against the Mariners on 31 May at 4:10PM ET, with settlement contingent on official MLB final statistics. The 18% implied probability for an Arizona victory reflects the Mariners' home-field advantage and recent form, though this figure warrants examination against historical matchup data and current roster composition. For automated trading systems, the settlement window extending to 7 June accounts for potential postponements; conditional orders should incorporate weather-delay logic given the Pacific Northwest's May precipitation patterns.

Arizona's 2024 campaign saw them finish with a .500 record against Seattle across their season series, suggesting the current odds may underweight the Diamondbacks' competitive capacity in this fixture. The Mariners' home record typically runs 3–5 percentage points stronger than road performance, a factor already priced into the 82% implied probability for Seattle. Traders evaluating this market programmatically should cross-reference recent pitching assignments—the scheduled starter matchup carries outsized weight in single-game MLB markets, as does bullpen availability following preceding games in the series.

Key catalysts include injury reports released 24–48 hours before first pitch and any late-inning roster adjustments. The Mariners' recent performance against left-handed pitchers and Arizona's platoon splits merit integration into conditional-order parameters. Settlement risk remains minimal given MLB's robust makeup-game protocols, though the 50-50 tie resolution clause applies only to cancellations without rescheduling, an outcome historically rare in May fixtures.

Methodology

We track Arizona Diamondbacks vs. Seattle Mariners on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Is this market available outside the US?

Polymarket App UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What does it cost to trade on Polymarket App UK?

Zero. Polymarket App UK routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.