MLB Stolen Bases Arb: 2.75% Guaranteed Profit on FanDuel vs. ProphetX
A 2.75% guaranteed return on a single MLB prop isn't glamorous. But it's also not a bet — it's a math problem with a correct answer. Today's signal flags a stolen bases Over on FanDuel at +1700, with the Under available at exchange pricing on the other side. Lock both, collect the spread.
Here's the full breakdown.
The Signal
| Field | Value | |---|---| | Sport | MLB | | Market | Batter Stolen Bases — Over | | FanDuel Price | +1700 | | Arb Profit | 2.75% | | Partner Book | ProphetX |
FanDuel is posting +1700 on a batter stolen bases Over. That's a juiced-up prop — the kind of long-shot line that typically reflects a "must happen multiple times" threshold, like a player stealing 2+ bases in a single game. The number looks huge, but the relevant question isn't whether the player will do it. It's whether the implied probability on both sides adds up to less than 100%.
It does. That's the arb.
Why Arbs Exist
Sportsbooks don't set prices by talking to each other. Each book runs its own model, uses its own data, and makes its own judgment calls about how to shade lines toward their liability exposure. FanDuel, in particular, is known for aggressive pricing on player props — sometimes inflating long-shot Overs to attract recreational volume, sometimes lagging on line movement when sharp action hits a correlated market elsewhere.
Pinnacle, which publishes extensively on line shopping and market efficiency, has documented consistently that prop markets on retail sportsbooks carry among the highest vig in any betting category. When one book is pricing a stolen bases prop at +1700 and a peer-to-peer exchange is offering the other side at a price that implies less than 100% combined probability, that gap is purely a product of disagreement between pricing models.
The exchange doesn't have the same structural incentive to shade the line. No house edge to protect. Just commission on winnings.
The Math, Plain English
Let's assume you want to arb $1,000 total across both sides. Here's how to split it.
Step 1: Convert the FanDuel price to implied probability.
+1700 in American odds = 100 / (1700 + 100) = 5.56% implied probability
Step 2: The Under side on ProphetX.
For the arb to yield 2.75%, the Under needs to be priced such that the combined implied probability across both sides lands at roughly 97.32% (i.e., 100% minus the 2.75% profit margin). That means the Under is implying approximately 91.76%.
91.76% implied probability converts to roughly -1108 in American odds — a heavy favorite on the Under, which is exactly what you'd expect when the Over is a +1700 long shot.
Step 3: Stake allocation.
To guarantee equal profit regardless of outcome:
- Over stake (FanDuel): ~$51.60
- Under stake (ProphetX): ~$948.40
- Total at risk: $1,000.00
If the Over hits:
$51.60 × 17 = $877.20 profit → net after $948.40 Under stake = ~$27.50 guaranteed
If the Under hits:
The Under pays out at ~-1108, so $948.40 wins roughly $85.60 → net after $51.60 Over stake = ~$27.50 guaranteed
Either way, you collect approximately $27.50 on $1,000 deployed — 2.75% with zero directional risk.
That's the arbitrage. It doesn't matter what the player does.
Why ProphetX Is the Right Side for the Under
The structural issue with arbing through two retail sportsbooks is that you're paying vig twice. One book juices the Over, the other juices the Under, and suddenly your theoretical arb margin shrinks or disappears entirely once you account for both take rates.
ProphetX is a peer-to-peer exchange. There's no built-in margin on the line itself — you're matching against another bettor, not against a book setting a vig. ProphetX charges commission on winnings only, which means the Under price you see is genuinely close to fair value. You're not eating a second round of juice.
That matters specifically for the Under side here. When the Under is implying ~91.76%, even a couple of percentage points of hidden vig on the retail version of that line would collapse the 2.75% profit margin into noise. On the exchange, the price is cleaner.
Limits are the other factor. Retail books are fast to flag accounts running systematic arbs on player props. Once you've hit the same prop market a few times at FanDuel, expect reduced limits or outright restrictions on those markets. ProphetX doesn't operate that way — you're betting peer-to-peer, and the exchange has no structural motivation to cut your action because you're profitable.
Execution Notes
- Move fast. +1700 on FanDuel won't stay there if the line is being watched. Player prop markets can gap quickly, especially mid-afternoon before first pitch.
- Check the Over threshold. Make sure you know exactly what "Over" means here — 1.5 stolen bases (i.e., 2+) is a different proposition than 0.5 (i.e., any steal). The arb math above holds regardless, but you need the Under on ProphetX to cover the same threshold.
- Confirm liquidity on ProphetX. Exchange markets sometimes have thin depth on player props. Verify the Under is available at the implied price before committing the Over side on FanDuel.
- Keep records. If you're running arbs systematically, tracking your implied probability on every bet helps you audit slippage over time. Losing 0.5% to execution friction on every arb erodes returns faster than most people account for.
Bottom Line
2.75% locked profit on an MLB stolen bases prop isn't a lottery ticket — it's a fee for doing the work of finding where two pricing systems disagree. FanDuel is generous on the Over at +1700. ProphetX offers the Under at exchange pricing without a second layer of vig eating into your margin.
The math is straightforward. The execution window is short.
If you're not already set up on the exchange side, ProphetX is the place to do it — peer-to-peer, commission-only model, no-vig pricing on the lines themselves. That's the structural advantage that makes arbs like this one actually work in practice.