Boston Red Sox vs. Cleveland Guardians

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Active sub-markets

Market context

The Boston Red Sox face the Cleveland Guardians on 29 May at 7:10 PM ET in an AL East matchup. Polymarket currently prices a Red Sox victory at 14%, implying roughly 86% probability for a Guardians win. This pricing reflects Cleveland's stronger 2025 regular season record and recent head-to-head performance, though the 7-to-1 odds against Boston suggest the market is pricing in more than baseline strength differential.

Historical context matters here: the Red Sox have won 9 of their last 15 meetings with Cleveland dating back to 2023, yet this season's form diverges sharply. Cleveland sits with a superior run differential and has won 11 of 15 games in May, whilst Boston has struggled with inconsistent pitching depth. When Polymarket prices a team at 14%, it typically reflects either genuine weakness or specific injury/roster concerns rather than random variance. The Guardians' bullpen has been particularly effective this season, which the market has priced in.

Traders should monitor starting pitcher assignments and any late roster moves before first pitch. Boston's recent injury reports—particularly regarding their rotation—could shift the probability if a key starter is unavailable. Cleveland's recent form suggests sustained competitiveness rather than a hot streak, making the current odds relatively stable unless significant news emerges. Settlement occurs 5 June, providing a week buffer for any postponements, though May weather in the Northeast rarely causes delays at this time of year.

Methodology

We track Boston Red Sox vs. Cleveland Guardians 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 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's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket UK 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.