Arizona Diamondbacks vs. Seattle Mariners

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Market context

The Arizona Diamondbacks travel to Seattle for a 4:10 PM ET start on 31 May, with the Mariners favoured at 75 per cent implied probability. The 25 per cent odds on Arizona reflect the visitor's disadvantage and recent form divergence between the clubs heading into late May. Seattle has maintained stronger consistency in the AL West, whilst Arizona's inconsistency through spring and early summer has made road matchups particularly challenging for the franchise.

Historically, the Diamondbacks perform better in their own ballpark, where they've managed above-.500 records in recent seasons despite middling road performances. The Mariners' home-field advantage at T-Mobile Park carries measurable weight in May contests; Seattle's record in home games typically outpaces road results by 3–5 percentage points. When Arizona visits the Pacific Northwest, the probability shift toward the home side has been consistent enough to anchor current market pricing near the 75–25 split.

Watch for starting pitcher announcements in the 48 hours before first pitch, as rotation decisions often shift these markets 5–8 percentage points either direction. Recent injury reports from both bullpens matter substantially; Seattle's relief depth has been questioned mid-season, whilst Arizona's starter availability has fluctuated. Weather conditions at T-Mobile Park—particularly wind direction affecting fly-ball carry—occasionally influence totals but rarely shift moneyline odds more than 2–3 points. Any late-breaking roster moves or unexpected absences from either lineup would be the primary catalyst for material repricing before settlement.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Is this market available outside the US?

Prediction Today 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 Prediction Today?

Zero. Prediction Today 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.