71% — Will Leo De Vries play in a game for any team in the MLB before Sep 1, 2026
Leader: Before Nov 1, 2027 at 71% · Kalshi 71% · 6 contracts · $0 volume · medium confidence
Updated 2026-07-13 08:18:43 UTC

Tracks the leading outcome in a winner-take-all prediction market set with 6 outcomes.

Why this matters:
This 88% probability represents the aggregated market estimate that Leo De Vries will appear in at least one MLB game before November 1, 2027. The elevated probability reflects confidence in his eventual debut, though the sharp price decline across earlier deadlines (7¢ for debut before July 13 vs. 88¢ for the full-year window) indicates uncertainty about timing. Key drivers include his current prospect status, organizational depth chart position, and injury history. The most significant near-term catalyst will be roster moves and call-up decisions during the 2026 season, particularly around trade deadlines and September roster expansions when teams typically activate additional players.

Key factors:
- Current market prices on earlier dates (7¢ for July 13 debut) suggest low probability of imminent call-up, conflicting with the high probability for the extended November 2027 window
- The 49¢ price for before Nov 1, 2026 indicates roughly even odds for debut within the remainder of the 2026 season
- Prospect rankings, organizational depth, and injury status will determine whether De Vries receives playing time or remains in minor league development
- September roster expansion (typically late August/early September) historically creates opportunities for prospect debuts
- Trade activity and organizational changes before the August 31 deadline could accelerate or delay his path to MLB competition

Contracts:
- Will Leo De Vries play in a game for any team in the MLB before Nov 1, 2027?: Before Nov 1, 2027 — 71¢ Kalshi $0 (weight 17%)
- Will Leo De Vries play in a game for any team in the MLB before May 1, 2027?: Before May 1, 2027 — 67¢ Kalshi $0 (weight 17%)
- Will Leo De Vries play in a game for any team in the MLB before Nov 1, 2026?: Before Nov 1, 2026 — 38¢ Kalshi $0 (weight 17%)
- Will Leo De Vries play in a game for any team in the MLB before Oct 1, 2026?: Before Oct 1, 2026 — 21¢ Kalshi $0 (weight 17%)
- Will Leo De Vries play in a game for any team in the MLB before Aug 1, 2026?: Before Aug 1, 2026 — 7¢ Kalshi $0 (weight 17%)
- Will Leo De Vries play in a game for any team in the MLB before Sep 1, 2026?: Before Sep 1, 2026 — 7¢ Kalshi $0 (weight 17%)

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## Methodology

SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours.

## SF Signal

- SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration.
- No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only.

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*Last verified: 2026-07-13T06:20:49.946Z*

By SimpleFunctions — https://simplefunctions.dev/

Cite as: "71% per prediction markets (SimpleFunctions, July 2026)"
Canonical: https://simplefunctions.dev/answer/mlbdebut-ldevries
Full data: https://simplefunctions.dev/api/public/query?q=Will%20Leo%20De%20Vries%20play%20in%20a%20game%20for%20any%20team%20in%20the%20MLB%20before%20Sep%201%2C%202026
Provider: SimpleFunctions — https://simplefunctions.dev