Boston Red Sox vs. Cleveland Guardians

Platform comparison

Active sub-markets

Market context

The Boston Red Sox travel to Cleveland for a day game on 31 May at 1:40 PM ET, with Polymarket currently pricing a Red Sox victory at 46 per cent. This represents a slight lean towards the Guardians, reflecting Cleveland's stronger recent form and home-field advantage. The settlement window extends to 7 June, allowing for postponements common in late May baseball when weather disruptions occur across the Midwest and Northeast.

Historical matchups between these franchises show competitive balance, though Cleveland has edged Boston in head-to-head records over the past three seasons. The Guardians' 2023 World Series run established them as a serious contender, whilst the Red Sox have undergone roster transitions that created inconsistency. Traders should note that May baseball carries elevated postponement risk; the Cleveland area experiences frequent spring thunderstorms that can delay or reschedule games, which would keep this contract open beyond the initial settlement date.

Pitching matchups and bullpen availability represent the primary catalysts traders should monitor before settlement. Starting pitcher announcements typically come 24 hours before game time, and injuries to key relievers—particularly in bullpen-dependent teams like Boston—can shift win probability meaningfully. Recent roster updates from both clubs should be cross-referenced with official MLB injury reports, as late-inning availability directly influences close-game outcomes. The conditional token mechanics on Polygon mean position holders can exit before game time if new information emerges that shifts the underlying probability.

Methodology

This page reviews Boston Red Sox vs. Cleveland Guardians across five venues. We show live odds for Polymarket-based markets (sourced from the Polygon order book); for other venues we list platform attributes, since the comparable contracts are not exposed via a public API on every venue. Every CTA points at Polymarket UK — the application we operate, where you trade directly against the Polymarket order book at 0% fees.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket UK, 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.

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.

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.