Boston Red Sox vs. Seattle Mariners

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Active sub-markets

Market context

Boston’s visit to Seattle comes with the Mariners carrying the stronger underlying shape into the series, which helps explain why a Boston win is priced at only 25% despite the short-term volatility of one MLB game. Seattle entered the set at 37-36 and first in the AL West, while Boston had just dropped four straight after a 4-3 defeat to Toronto, leaving them 29-43 overall and still searching for steadier road form[1][2][3]. Comparable recent cases point in the same direction: a team with the better record, home field, and a more settled run of pitching usually draws the shorter side of the market, especially when the visitor is carrying a losing streak and weaker results against similar opponents[1][3].

For traders, the main catalysts are lineup confirmation and late injury updates. The Red Sox have been managing absences, including Roman Anthony on the 10-day injured list with a finger sprain and Nick Sogard out with an oblique strain, while Seattle has also been juggling day-to-day issues and injuries that affect bench flexibility[1]. The Globe’s preview noted Boston’s struggles against right-handers and AL West opponents, which matters if Seattle sticks with a right-handed starter and can keep its bullpen rested for leverage innings[3]. Seattle’s own roster move — recalling Connor Joe to add coverage against left-handed pitching — is a small but relevant sign that the club is still optimising match-up usage rather than settling into a fixed look[1].

Sources: 1 · 2 · 3 · 4 · 5

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

Where can I trade this market with the lowest fees?

On Sport Prediction, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

What does it cost to trade on Sport Prediction?

Zero. Sport Prediction 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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Sport Prediction triggers a quick verification flow that finishes in 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.